using System;
using System.IO;
using System.Collections;
using System.Collections.Generic;
using System.Runtime;
using System.Runtime.InteropServices;

using PickGold.Exceptions;


namespace PickGold.Zip
{
	/// <summary>
	///   The ZipFile type represents a zip archive file.
	/// </summary>
	///
	/// <remarks>
	/// <para>
	///   This is the main type in the DotNetZip class library. This class reads and
	///   writes zip files, as defined in the <see
	///   href="http://www.pkware.com/documents/casestudies/APPNOTE.TXT">specification
	///   for zip files described by PKWare</see>.  The compression for this
	///   implementation is provided by a managed-code version of Zlib, included with
	///   DotNetZip in the classes in the PickGold.Zlib namespace.
	/// </para>
	///
	/// <para>
	///   This class provides a general purpose zip file capability.  Use it to read,
	///   create, or update zip files.  When you want to create zip files using a
	///   <c>Stream</c> type to write the zip file, you may want to consider the <see
	///   cref="ZipOutputStream"/> class.
	/// </para>
	///
	/// <para>
	///   Both the <c>ZipOutputStream</c> class and the <c>ZipFile</c> class can
	///   be used to create zip files. Both of them support many of the common zip
	///   features, including Unicode, different compression methods and levels,
	///   and ZIP64. They provide very similar performance when creating zip
	///   files.
	/// </para>
	///
	/// <para>
	///   The <c>ZipFile</c> class is generally easier to use than
	///   <c>ZipOutputStream</c> and should be considered a higher-level interface.  For
	///   example, when creating a zip file via calls to the <c>PutNextEntry()</c> and
	///   <c>Write()</c> methods on the <c>ZipOutputStream</c> class, the caller is
	///   responsible for opening the file, reading the bytes from the file, writing
	///   those bytes into the <c>ZipOutputStream</c>, setting the attributes on the
	///   <c>ZipEntry</c>, and setting the created, last modified, and last accessed
	///   timestamps on the zip entry. All of these things are done automatically by a
	///   call to <see cref="ZipFile.AddFile(string,string)">ZipFile.AddFile()</see>.
	///   For this reason, the <c>ZipOutputStream</c> is generally recommended for use
	///   only when your application emits arbitrary data, not necessarily data from a
	///   filesystem file, directly into a zip file, and does so using a <c>Stream</c>
	///   metaphor.
	/// </para>
	///
	/// <para>
	///   Aside from the differences in programming model, there are other
	///   differences in capability between the two classes.
	/// </para>
	///
	/// <list type="bullet">
	///   <item>
	///     <c>ZipFile</c> can be used to read and extract zip files, in addition to
	///     creating zip files. <c>ZipOutputStream</c> cannot read zip files. If you want
	///     to use a stream to read zip files, check out the <see cref="ZipInputStream"/> class.
	///   </item>
	///
	///   <item>
	///     <c>ZipOutputStream</c> does not support the creation of segmented or spanned
	///     zip files.
	///   </item>
	///
	///   <item>
	///     <c>ZipOutputStream</c> cannot produce a self-extracting archive.
	///   </item>
	/// </list>
	///
	/// <para>
	///   Be aware that the <c>ZipFile</c> class implements the <see
	///   cref="System.IDisposable"/> interface.  In order for <c>ZipFile</c> to
	///   produce a valid zip file, you use use it within a using clause (<c>Using</c>
	///   in VB), or call the <c>Dispose()</c> method explicitly.  See the examples
	///   for how to employ a using clause.
	/// </para>
	///
	/// </remarks>
	[Guid("ebc25cf6-9120-4283-b972-0e5520d00005")]
	[ComVisible(true)]
#if !NETCF
	[ClassInterface(ClassInterfaceType.AutoDispatch)]
#endif
	public partial class ZipFile :
	IEnumerable,
	IEnumerable<ZipEntry>,
	IDisposable
	{

		#region public properties

		/// <summary>
		/// Indicates whether to perform a full scan of the zip file when reading it.
		/// </summary>
		///
		/// <remarks>
		///
		/// <para>
		///   You almost never want to use this property.
		/// </para>
		///
		/// <para>
		///   When reading a zip file, if this flag is <c>true</c> (<c>True</c> in
		///   VB), the entire zip archive will be scanned and searched for entries.
		///   For large archives, this can take a very, long time. The much more
		///   efficient default behavior is to read the zip directory, which is
		///   stored at the end of the zip file. But, in some cases the directory is
		///   corrupted and you need to perform a full scan of the zip file to
		///   determine the contents of the zip file. This property lets you do
		///   that, when necessary.
		/// </para>
		///
		/// <para>
		///   This flag is effective only when calling <see
		///   cref="Initialize(string)"/>. Normally you would read a ZipFile with the
		///   static <see cref="ZipFile.Read(String)">ZipFile.Read</see>
		///   method. But you can't set the <c>FullScan</c> property on the
		///   <c>ZipFile</c> instance when you use a static factory method like
		///   <c>ZipFile.Read</c>.
		/// </para>
		///
		/// </remarks>
		///
		/// <example>
		///
		///   This example shows how to read a zip file using the full scan approach,
		///   and then save it, thereby producing a corrected zip file.
		///
		/// <code lang="C#">
		/// using (var zip = new ZipFile())
		/// {
		///     zip.FullScan = true;
		///     zip.Initialize(zipFileName);
		///     zip.Save(newName);
		/// }
		/// </code>
		///
		/// <code lang="VB">
		/// Using zip As New ZipFile
		///     zip.FullScan = True
		///     zip.Initialize(zipFileName)
		///     zip.Save(newName)
		/// End Using
		/// </code>
		/// </example>
		///
		public bool FullScan
		{
			get;
			set;
		}


		/// <summary>
		///   Whether to sort the ZipEntries before saving the file.
		/// </summary>
		///
		/// <remarks>
		///   The default is false.  If you have a large number of zip entries, the sort
		///   alone can consume significant time.
		/// </remarks>
		///
		/// <example>
		/// <code lang="C#">
		/// using (var zip = new ZipFile())
		/// {
		///     zip.AddFiles(filesToAdd);
		///     zip.SortEntriesBeforeSaving = true;
		///     zip.Save(name);
		/// }
		/// </code>
		///
		/// <code lang="VB">
		/// Using zip As New ZipFile
		///     zip.AddFiles(filesToAdd)
		///     zip.SortEntriesBeforeSaving = True
		///     zip.Save(name)
		/// End Using
		/// </code>
		/// </example>
		///
		public bool SortEntriesBeforeSaving
		{
			get;
			set;
		}



		/// <summary>
		///   Indicates whether NTFS Reparse Points, like junctions, should be
		///   traversed during calls to <c>AddDirectory()</c>.
		/// </summary>
		///
		/// <remarks>
		///   By default, calls to AddDirectory() will traverse NTFS reparse
		///   points, like mounted volumes, and directory junctions.  An example
		///   of a junction is the "My Music" directory in Windows Vista.  In some
		///   cases you may not want DotNetZip to traverse those directories.  In
		///   that case, set this property to false.
		/// </remarks>
		///
		/// <example>
		/// <code lang="C#">
		/// using (var zip = new ZipFile())
		/// {
		///     zip.AddDirectoryWillTraverseReparsePoints = false;
		///     zip.AddDirectory(dirToZip,"fodder");
		///     zip.Save(zipFileToCreate);
		/// }
		/// </code>
		/// </example>
		public bool AddDirectoryWillTraverseReparsePoints { get; set; }


		/// <summary>
		///   Size of the IO buffer used while saving.
		/// </summary>
		///
		/// <remarks>
		///
		/// <para>
		///   First, let me say that you really don't need to bother with this.  It is
		///   here to allow for optimizations that you probably won't make! It will work
		///   fine if you don't set or get this property at all. Ok?
		/// </para>
		///
		/// <para>
		///   Now that we have <em>that</em> out of the way, the fine print: This
		///   property affects the size of the buffer that is used for I/O for each
		///   entry contained in the zip file. When a file is read in to be compressed,
		///   it uses a buffer given by the size here.  When you update a zip file, the
		///   data for unmodified entries is copied from the first zip file to the
		///   other, through a buffer given by the size here.
		/// </para>
		///
		/// <para>
		///   Changing the buffer size affects a few things: first, for larger buffer
		///   sizes, the memory used by the <c>ZipFile</c>, obviously, will be larger
		///   during I/O operations.  This may make operations faster for very much
		///   larger files.  Last, for any given entry, when you use a larger buffer
		///   there will be fewer progress events during I/O operations, because there's
		///   one progress event generated for each time the buffer is filled and then
		///   emptied.
		/// </para>
		///
		/// <para>
		///   The default buffer size is 8k.  Increasing the buffer size may speed
		///   things up as you compress larger files.  But there are no hard-and-fast
		///   rules here, eh?  You won't know til you test it.  And there will be a
		///   limit where ever larger buffers actually slow things down.  So as I said
		///   in the beginning, it's probably best if you don't set or get this property
		///   at all.
		/// </para>
		///
		/// </remarks>
		///
		/// <example>
		/// This example shows how you might set a large buffer size for efficiency when
		/// dealing with zip entries that are larger than 1gb.
		/// <code lang="C#">
		/// using (ZipFile zip = new ZipFile())
		/// {
		///     zip.SaveProgress += this.zip1_SaveProgress;
		///     zip.AddDirectory(directoryToZip, "");
		///     zip.UseZip64WhenSaving = Zip64Option.Always;
		///     zip.BufferSize = 65536*8; // 65536 * 8 = 512k
		///     zip.Save(ZipFileToCreate);
		/// }
		/// </code>
		/// </example>

		public int BufferSize
		{
			get { return _BufferSize; }
			set { _BufferSize = value; }
		}

		/// <summary>
		///   Size of the work buffer to use for the ZLIB codec during compression.
		/// </summary>
		///
		/// <remarks>
		///   <para>
		///     When doing ZLIB or Deflate compression, the library fills a buffer,
		///     then passes it to the compressor for compression. Then the library
		///     reads out the compressed bytes. This happens repeatedly until there
		///     is no more uncompressed data to compress. This property sets the
		///     size of the buffer that will be used for chunk-wise compression. In
		///     order for the setting to take effect, your application needs to set
		///     this property before calling one of the <c>ZipFile.Save()</c>
		///     overloads.
		///   </para>
		///   <para>
		///     Setting this affects the performance and memory efficiency of
		///     compression and decompression. For larger files, setting this to a
		///     larger size may improve compression performance, but the exact
		///     numbers vary depending on available memory, the size of the streams
		///     you are compressing, and a bunch of other variables. I don't have
		///     good firm recommendations on how to set it.  You'll have to test it
		///     yourself. Or just leave it alone and accept the default.
		///   </para>
		/// </remarks>
		public int CodecBufferSize
		{
			get;
			set;
		}

		/// <summary>
		///   Indicates whether extracted files should keep their paths as
		///   stored in the zip archive.
		/// </summary>
		///
		/// <remarks>
		///  <para>
		///    This property affects Extraction.  It is not used when creating zip
		///    archives.
		///  </para>
		///
		///  <para>
		///    With this property set to <c>false</c>, the default, extracting entries
		///    from a zip file will create files in the filesystem that have the full
		///    path associated to the entry within the zip file.  With this property set
		///    to <c>true</c>, extracting entries from the zip file results in files
		///    with no path: the folders are "flattened."
		///  </para>
		///
		///  <para>
		///    An example: suppose the zip file contains entries /directory1/file1.txt and
		///    /directory2/file2.txt.  With <c>FlattenFoldersOnExtract</c> set to false,
		///    the files created will be \directory1\file1.txt and \directory2\file2.txt.
		///    With the property set to true, the files created are file1.txt and file2.txt.
		///  </para>
		///
		/// </remarks>
		public bool FlattenFoldersOnExtract
		{
			get;
			set;
		}


		/// <summary>
		///   The compression strategy to use for all entries.
		/// </summary>
		///
		/// <remarks>
		///   Set the Strategy used by the ZLIB-compatible compressor, when
		///   compressing entries using the DEFLATE method. Different compression
		///   strategies work better on different sorts of data. The strategy
		///   parameter can affect the compression ratio and the speed of
		///   compression but not the correctness of the compresssion.  For more
		///   information see <see
		///   cref="PickGold.Zlib.CompressionStrategy">PickGold.Zlib.CompressionStrategy</see>.
		/// </remarks>
		public PickGold.Zlib.CompressionStrategy Strategy
		{
			get { return _Strategy; }
			set { _Strategy = value; }
		}


		/// <summary>
		///   The name of the <c>ZipFile</c>, on disk.
		/// </summary>
		///
		/// <remarks>
		///
		/// <para>
		///   When the <c>ZipFile</c> instance was created by reading an archive using
		///   one of the <c>ZipFile.Read</c> methods, this property represents the name
		///   of the zip file that was read.  When the <c>ZipFile</c> instance was
		///   created by using the no-argument constructor, this value is <c>null</c>
		///   (<c>Nothing</c> in VB).
		/// </para>
		///
		/// <para>
		///   If you use the no-argument constructor, and you then explicitly set this
		///   property, when you call <see cref="ZipFile.Save()"/>, this name will
		///   specify the name of the zip file created.  Doing so is equivalent to
		///   calling <see cref="ZipFile.Save(String)"/>.  When instantiating a
		///   <c>ZipFile</c> by reading from a stream or byte array, the <c>Name</c>
		///   property remains <c>null</c>.  When saving to a stream, the <c>Name</c>
		///   property is implicitly set to <c>null</c>.
		/// </para>
		/// </remarks>
		public string Name
		{
			get { return _name; }
			set { _name = value; }
		}


		/// <summary>
		///   Sets the compression level to be used for entries subsequently added to
		///   the zip archive.
		/// </summary>
		///
		/// <remarks>
		///  <para>
		///    Varying the compression level used on entries can affect the
		///    size-vs-speed tradeoff when compression and decompressing data streams
		///    or files.
		///  </para>
		///
		///  <para>
		///    As with some other properties on the <c>ZipFile</c> class, like <see
		///    cref="Password"/>, <see cref="Encryption"/>, and <see
		///    cref="ZipErrorAction"/>, setting this property on a <c>ZipFile</c>
		///    instance will cause the specified <c>CompressionLevel</c> to be used on all
		///    <see cref="ZipEntry"/> items that are subsequently added to the
		///    <c>ZipFile</c> instance. If you set this property after you have added
		///    items to the <c>ZipFile</c>, but before you have called <c>Save()</c>,
		///    those items will not use the specified compression level.
		///  </para>
		///
		///  <para>
		///    If you do not set this property, the default compression level is used,
		///    which normally gives a good balance of compression efficiency and
		///    compression speed.  In some tests, using <c>BestCompression</c> can
		///    double the time it takes to compress, while delivering just a small
		///    increase in compression efficiency.  This behavior will vary with the
		///    type of data you compress.  If you are in doubt, just leave this setting
		///    alone, and accept the default.
		///  </para>
		/// </remarks>
		public PickGold.Zlib.CompressionLevel CompressionLevel
		{
			get;
			set;
		}

		/// <summary>
		///   The compression method for the zipfile.
		/// </summary>
		/// <remarks>
		///   <para>
		///     By default, the compression method is <c>CompressionMethod.Deflate.</c>
		///   </para>
		/// </remarks>
		/// <seealso cref="PickGold.Zip.CompressionMethod" />
		public PickGold.Zip.CompressionMethod CompressionMethod
		{
			get
			{
				return _compressionMethod;
			}
			set
			{
				_compressionMethod = value;
			}
		}



		/// <summary>
		///   A comment attached to the zip archive.
		/// </summary>
		///
		/// <remarks>
		///
		/// <para>
		///   This property is read/write. It allows the application to specify a
		///   comment for the <c>ZipFile</c>, or read the comment for the
		///   <c>ZipFile</c>.  After setting this property, changes are only made
		///   permanent when you call a <c>Save()</c> method.
		/// </para>
		///
		/// <para>
		///   According to <see
		///   href="http://www.pkware.com/documents/casestudies/APPNOTE.TXT">PKWARE's
		///   zip specification</see>, the comment is not encrypted, even if there is a
		///   password set on the zip file.
		/// </para>
		///
		/// <para>
		///   The specification does not describe how to indicate the encoding used
		///   on a comment string. Many "compliant" zip tools and libraries use
		///   IBM437 as the code page for comments; DotNetZip, too, follows that
		///   practice.  On the other hand, there are situations where you want a
		///   Comment to be encoded with something else, for example using code page
		///   950 "Big-5 Chinese". To fill that need, DotNetZip will encode the
		///   comment following the same procedure it follows for encoding
		///   filenames: (a) if <see cref="AlternateEncodingUsage"/> is
		///   <c>Never</c>, it uses the default encoding (IBM437). (b) if <see
		///   cref="AlternateEncodingUsage"/> is <c>Always</c>, it always uses the
		///   alternate encoding (<see cref="AlternateEncoding"/>). (c) if <see
		///   cref="AlternateEncodingUsage"/> is <c>AsNecessary</c>, it uses the
		///   alternate encoding only if the default encoding is not sufficient for
		///   encoding the comment - in other words if decoding the result does not
		///   produce the original string.  This decision is taken at the time of
		///   the call to <c>ZipFile.Save()</c>.
		/// </para>
		///
		/// <para>
		///   When creating a zip archive using this library, it is possible to change
		///   the value of <see cref="AlternateEncoding" /> between each
		///   entry you add, and between adding entries and the call to
		///   <c>Save()</c>. Don't do this.  It will likely result in a zip file that is
		///   not readable by any tool or application.  For best interoperability, leave
		///   <see cref="AlternateEncoding"/> alone, or specify it only
		///   once, before adding any entries to the <c>ZipFile</c> instance.
		/// </para>
		///
		/// </remarks>
		public string Comment
		{
			get { return _Comment; }
			set
			{
				_Comment = value;
				_contentsChanged = true;
			}
		}




		/// <summary>
		///   Specifies whether the Creation, Access, and Modified times for entries
		///   added to the zip file will be emitted in &#147;Windows format&#148;
		///   when the zip archive is saved.
		/// </summary>
		///
		/// <remarks>
		/// <para>
		///   An application creating a zip archive can use this flag to explicitly
		///   specify that the file times for the entries should or should not be stored
		///   in the zip archive in the format used by Windows. By default this flag is
		///   <c>true</c>, meaning the Windows-format times are stored in the zip
		///   archive.
		/// </para>
		///
		/// <para>
		///   When adding an entry from a file or directory, the Creation (<see
		///   cref="ZipEntry.CreationTime"/>), Access (<see
		///   cref="ZipEntry.AccessedTime"/>), and Modified (<see
		///   cref="ZipEntry.ModifiedTime"/>) times for the given entry are
		///   automatically set from the filesystem values. When adding an entry from a
		///   stream or string, all three values are implicitly set to
		///   <c>DateTime.Now</c>.  Applications can also explicitly set those times by
		///   calling <see cref="ZipEntry.SetEntryTimes(DateTime, DateTime,
		///   DateTime)"/>.
		/// </para>
		///
		/// <para>
		///   <see
		///   href="http://www.pkware.com/documents/casestudies/APPNOTE.TXT">PKWARE's
		///   zip specification</see> describes multiple ways to format these times in a
		///   zip file. One is the format Windows applications normally use: 100ns ticks
		///   since January 1, 1601 UTC.  The other is a format Unix applications typically
		///   use: seconds since January 1, 1970 UTC.  Each format can be stored in an
		///   "extra field" in the zip entry when saving the zip archive. The former
		///   uses an extra field with a Header Id of 0x000A, while the latter uses a
		///   header ID of 0x5455, although you probably don't need to know that.
		/// </para>
		///
		/// <para>
		///   Not all tools and libraries can interpret these fields.  Windows
		///   compressed folders is one that can read the Windows Format timestamps,
		///   while I believe <see href="http://www.info-zip.org/">the Infozip
		///   tools</see> can read the Unix format timestamps. Some tools and libraries
		///   may be able to read only one or the other. DotNetZip can read or write
		///   times in either or both formats.
		/// </para>
		///
		/// <para>
		///   The times stored are taken from <see cref="ZipEntry.ModifiedTime"/>, <see
		///   cref="ZipEntry.AccessedTime"/>, and <see cref="ZipEntry.CreationTime"/>.
		/// </para>
		///
		/// <para>
		///   The value set here applies to all entries subsequently added to the
		///   <c>ZipFile</c>.
		/// </para>
		///
		/// <para>
		///   This property is not mutually exclusive of the <see
		///   cref="EmitTimesInUnixFormatWhenSaving" /> property. It is possible and
		///   legal and valid to produce a zip file that contains timestamps encoded in
		///   the Unix format as well as in the Windows format, in addition to the <see
		///   cref="ZipEntry.LastModified">LastModified</see> time attached to each
		///   entry in the archive, a time that is always stored in "DOS format". And,
		///   notwithstanding the names PKWare uses for these time formats, any of them
		///   can be read and written by any computer, on any operating system.  But,
		///   there are no guarantees that a program running on Mac or Linux will
		///   gracefully handle a zip file with "Windows" formatted times, or that an
		///   application that does not use DotNetZip but runs on Windows will be able to
		///   handle file times in Unix format.
		/// </para>
		///
		/// <para>
		///   When in doubt, test.  Sorry, I haven't got a complete list of tools and
		///   which sort of timestamps they can use and will tolerate.  If you get any
		///   good information and would like to pass it on, please do so and I will
		///   include that information in this documentation.
		/// </para>
		/// </remarks>
		///
		/// <example>
		///   This example shows how to save a zip file that contains file timestamps
		///   in a format normally used by Unix.
		/// <code lang="C#">
		/// using (var zip = new ZipFile())
		/// {
		///     // produce a zip file the Mac will like
		///     zip.EmitTimesInWindowsFormatWhenSaving = false;
		///     zip.EmitTimesInUnixFormatWhenSaving = true;
		///     zip.AddDirectory(directoryToZip, "files");
		///     zip.Save(outputFile);
		/// }
		/// </code>
		///
		/// <code lang="VB">
		/// Using zip As New ZipFile
		///     '' produce a zip file the Mac will like
		///     zip.EmitTimesInWindowsFormatWhenSaving = False
		///     zip.EmitTimesInUnixFormatWhenSaving = True
		///     zip.AddDirectory(directoryToZip, "files")
		///     zip.Save(outputFile)
		/// End Using
		/// </code>
		/// </example>
		///
		/// <seealso cref="ZipEntry.EmitTimesInWindowsFormatWhenSaving" />
		/// <seealso cref="EmitTimesInUnixFormatWhenSaving" />
		public bool EmitTimesInWindowsFormatWhenSaving
		{
			get
			{
				return _emitNtfsTimes;
			}
			set
			{
				_emitNtfsTimes = value;
			}
		}


		/// <summary>
		/// Specifies whether the Creation, Access, and Modified times
		/// for entries added to the zip file will be emitted in "Unix(tm)
		/// format" when the zip archive is saved.
		/// </summary>
		///
		/// <remarks>
		/// <para>
		///   An application creating a zip archive can use this flag to explicitly
		///   specify that the file times for the entries should or should not be stored
		///   in the zip archive in the format used by Unix. By default this flag is
		///   <c>false</c>, meaning the Unix-format times are not stored in the zip
		///   archive.
		/// </para>
		///
		/// <para>
		///   When adding an entry from a file or directory, the Creation (<see
		///   cref="ZipEntry.CreationTime"/>), Access (<see
		///   cref="ZipEntry.AccessedTime"/>), and Modified (<see
		///   cref="ZipEntry.ModifiedTime"/>) times for the given entry are
		///   automatically set from the filesystem values. When adding an entry from a
		///   stream or string, all three values are implicitly set to DateTime.Now.
		///   Applications can also explicitly set those times by calling <see
		///   cref="ZipEntry.SetEntryTimes(DateTime, DateTime, DateTime)"/>.
		/// </para>
		///
		/// <para>
		///   <see
		///   href="http://www.pkware.com/documents/casestudies/APPNOTE.TXT">PKWARE's
		///   zip specification</see> describes multiple ways to format these times in a
		///   zip file. One is the format Windows applications normally use: 100ns ticks
		///   since January 1, 1601 UTC.  The other is a format Unix applications
		///   typically use: seconds since January 1, 1970 UTC.  Each format can be
		///   stored in an "extra field" in the zip entry when saving the zip
		///   archive. The former uses an extra field with a Header Id of 0x000A, while
		///   the latter uses a header ID of 0x5455, although you probably don't need to
		///   know that.
		/// </para>
		///
		/// <para>
		///   Not all tools and libraries can interpret these fields.  Windows
		///   compressed folders is one that can read the Windows Format timestamps,
		///   while I believe the <see href="http://www.info-zip.org/">Infozip</see>
		///   tools can read the Unix format timestamps. Some tools and libraries may be
		///   able to read only one or the other.  DotNetZip can read or write times in
		///   either or both formats.
		/// </para>
		///
		/// <para>
		///   The times stored are taken from <see cref="ZipEntry.ModifiedTime"/>, <see
		///   cref="ZipEntry.AccessedTime"/>, and <see cref="ZipEntry.CreationTime"/>.
		/// </para>
		///
		/// <para>
		///   This property is not mutually exclusive of the <see
		///   cref="EmitTimesInWindowsFormatWhenSaving" /> property. It is possible and
		///   legal and valid to produce a zip file that contains timestamps encoded in
		///   the Unix format as well as in the Windows format, in addition to the <see
		///   cref="ZipEntry.LastModified">LastModified</see> time attached to each
		///   entry in the zip archive, a time that is always stored in "DOS
		///   format". And, notwithstanding the names PKWare uses for these time
		///   formats, any of them can be read and written by any computer, on any
		///   operating system.  But, there are no guarantees that a program running on
		///   Mac or Linux will gracefully handle a zip file with "Windows" formatted
		///   times, or that an application that does not use DotNetZip but runs on
		///   Windows will be able to handle file times in Unix format.
		/// </para>
		///
		/// <para>
		///   When in doubt, test.  Sorry, I haven't got a complete list of tools and
		///   which sort of timestamps they can use and will tolerate.  If you get any
		///   good information and would like to pass it on, please do so and I will
		///   include that information in this documentation.
		/// </para>
		/// </remarks>
		///
		/// <seealso cref="ZipEntry.EmitTimesInUnixFormatWhenSaving" />
		/// <seealso cref="EmitTimesInWindowsFormatWhenSaving" />
		public bool EmitTimesInUnixFormatWhenSaving
		{
			get
			{
				return _emitUnixTimes;
			}
			set
			{
				_emitUnixTimes = value;
			}
		}



		/// <summary>
		///   Indicates whether verbose output is sent to the <see
		///   cref="StatusMessageTextWriter"/> during <c>AddXxx()</c> and
		///   <c>ReadXxx()</c> operations.
		/// </summary>
		///
		/// <remarks>
		///   This is a <em>synthetic</em> property.  It returns true if the <see
		///   cref="StatusMessageTextWriter"/> is non-null.
		/// </remarks>
		internal bool Verbose
		{
			get { return (_StatusMessageTextWriter != null); }
		}


		/// <summary>
		///   Returns true if an entry by the given name exists in the ZipFile.
		/// </summary>
		///
		/// <param name='name'>the name of the entry to find</param>
		/// <returns>true if an entry with the given name exists; otherwise false.
		/// </returns>
		public bool ContainsEntry(string name)
		{
			// workitem 12534
			return _entries.ContainsKey(SharedUtilities.NormalizePathForUseInZipFile(name));
		}



		/// <summary>
		///   Indicates whether to perform case-sensitive matching on the filename when
		///   retrieving entries in the zipfile via the string-based indexer.
		/// </summary>
		///
		/// <remarks>
		///   The default value is <c>false</c>, which means don't do case-sensitive
		///   matching. In other words, retrieving zip["ReadMe.Txt"] is the same as
		///   zip["readme.txt"].  It really makes sense to set this to <c>true</c> only
		///   if you are not running on Windows, which has case-insensitive
		///   filenames. But since this library is not built for non-Windows platforms,
		///   in most cases you should just leave this property alone.
		/// </remarks>
		public bool CaseSensitiveRetrieval
		{
			get
			{
				return _CaseSensitiveRetrieval;
			}

			set
			{
				// workitem 9868
				if (value != _CaseSensitiveRetrieval)
				{
					_CaseSensitiveRetrieval = value;
					_initEntriesDictionary();
				}
			}
		}


		/// <summary>
		///   Indicates whether to encode entry filenames and entry comments using Unicode
		///   (UTF-8).
		/// </summary>
		///
		/// <remarks>
		/// <para>
		///   <see href="http://www.pkware.com/documents/casestudies/APPNOTE.TXT">The
		///   PKWare zip specification</see> provides for encoding file names and file
		///   comments in either the IBM437 code page, or in UTF-8.  This flag selects
		///   the encoding according to that specification.  By default, this flag is
		///   false, and filenames and comments are encoded into the zip file in the
		///   IBM437 codepage.  Setting this flag to true will specify that filenames
		///   and comments that cannot be encoded with IBM437 will be encoded with
		///   UTF-8.
		/// </para>
		///
		/// <para>
		///   Zip files created with strict adherence to the PKWare specification with
		///   respect to UTF-8 encoding can contain entries with filenames containing
		///   any combination of Unicode characters, including the full range of
		///   characters from Chinese, Latin, Hebrew, Greek, Cyrillic, and many other
		///   alphabets.  However, because at this time, the UTF-8 portion of the PKWare
		///   specification is not broadly supported by other zip libraries and
		///   utilities, such zip files may not be readable by your favorite zip tool or
		///   archiver. In other words, interoperability will decrease if you set this
		///   flag to true.
		/// </para>
		///
		/// <para>
		///   In particular, Zip files created with strict adherence to the PKWare
		///   specification with respect to UTF-8 encoding will not work well with
		///   Explorer in Windows XP or Windows Vista, because Windows compressed
		///   folders, as far as I know, do not support UTF-8 in zip files.  Vista can
		///   read the zip files, but shows the filenames incorrectly. Unpacking from
		///   Windows Vista Explorer will result in filenames that have rubbish
		///   characters in place of the high-order UTF-8 bytes.
		/// </para>
		///
		/// <para>
		///   Also, zip files that use UTF-8 encoding will not work well with Java
		///   applications that use the java.util.zip classes, as of v5.0 of the Java
		///   runtime. The Java runtime does not correctly implement the PKWare
		///   specification in this regard.
		/// </para>
		///
		/// <para>
		///   As a result, we have the unfortunate situation that "correct" behavior by
		///   the DotNetZip library with regard to Unicode encoding of filenames during
		///   zip creation will result in zip files that are readable by strictly
		///   compliant and current tools (for example the most recent release of the
		///   commercial WinZip tool); but these zip files will not be readable by
		///   various other tools or libraries, including Windows Explorer.
		/// </para>
		///
		/// <para>
		///   The DotNetZip library can read and write zip files with UTF8-encoded
		///   entries, according to the PKware spec.  If you use DotNetZip for both
		///   creating and reading the zip file, and you use UTF-8, there will be no
		///   loss of information in the filenames. For example, using a self-extractor
		///   created by this library will allow you to unpack files correctly with no
		///   loss of information in the filenames.
		/// </para>
		///
		/// <para>
		///   If you do not set this flag, it will remain false.  If this flag is false,
		///   your <c>ZipFile</c> will encode all filenames and comments using the
		///   IBM437 codepage.  This can cause "loss of information" on some filenames,
		///   but the resulting zipfile will be more interoperable with other
		///   utilities. As an example of the loss of information, diacritics can be
		///   lost.  The o-tilde character will be down-coded to plain o.  The c with a
		///   cedilla (Unicode 0xE7) used in Portugese will be downcoded to a c.
		///   Likewise, the O-stroke character (Unicode 248), used in Danish and
		///   Norwegian, will be down-coded to plain o. Chinese characters cannot be
		///   represented in codepage IBM437; when using the default encoding, Chinese
		///   characters in filenames will be represented as ?. These are all examples
		///   of "information loss".
		/// </para>
		///
		/// <para>
		///   The loss of information associated to the use of the IBM437 encoding is
		///   inconvenient, and can also lead to runtime errors. For example, using
		///   IBM437, any sequence of 4 Chinese characters will be encoded as ????.  If
		///   your application creates a <c>ZipFile</c>, then adds two files, each with
		///   names of four Chinese characters each, this will result in a duplicate
		///   filename exception.  In the case where you add a single file with a name
		///   containing four Chinese characters, calling Extract() on the entry that
		///   has question marks in the filename will result in an exception, because
		///   the question mark is not legal for use within filenames on Windows.  These
		///   are just a few examples of the problems associated to loss of information.
		/// </para>
		///
		/// <para>
		///   This flag is independent of the encoding of the content within the entries
		///   in the zip file. Think of the zip file as a container - it supports an
		///   encoding.  Within the container are other "containers" - the file entries
		///   themselves.  The encoding within those entries is independent of the
		///   encoding of the zip archive container for those entries.
		/// </para>
		///
		/// <para>
		///   Rather than specify the encoding in a binary fashion using this flag, an
		///   application can specify an arbitrary encoding via the <see
		///   cref="ProvisionalAlternateEncoding"/> property.  Setting the encoding
		///   explicitly when creating zip archives will result in non-compliant zip
		///   files that, curiously, are fairly interoperable.  The challenge is, the
		///   PKWare specification does not provide for a way to specify that an entry
		///   in a zip archive uses a code page that is neither IBM437 nor UTF-8.
		///   Therefore if you set the encoding explicitly when creating a zip archive,
		///   you must take care upon reading the zip archive to use the same code page.
		///   If you get it wrong, the behavior is undefined and may result in incorrect
		///   filenames, exceptions, stomach upset, hair loss, and acne.
		/// </para>
		/// </remarks>
		/// <seealso cref="ProvisionalAlternateEncoding"/>
		[Obsolete("Beginning with v1.9.1.6 of DotNetZip, this property is obsolete.  It will be removed in a future version of the library. Your applications should  use AlternateEncoding and AlternateEncodingUsage instead.")]
		public bool UseUnicodeAsNecessary
		{
			get
			{
				return (_alternateEncoding == System.Text.Encoding.GetEncoding("UTF-8")) &&
					(_alternateEncodingUsage == ZipOption.AsNecessary);
			}
			set
			{
				if (value)
				{
					_alternateEncoding = System.Text.Encoding.GetEncoding("UTF-8");
					_alternateEncodingUsage = ZipOption.AsNecessary;

				}
				else
				{
					_alternateEncoding = PickGold.Zip.ZipFile.DefaultEncoding;
					_alternateEncodingUsage = ZipOption.Never;
				}
			}
		}


		/// <summary>
		///   Specify whether to use ZIP64 extensions when saving a zip archive.
		/// </summary>
		///
		/// <remarks>
		///
		/// <para>
		///   When creating a zip file, the default value for the property is <see
		///   cref="Zip64Option.Never"/>. <see cref="Zip64Option.AsNecessary"/> is
		///   safest, in the sense that you will not get an Exception if a pre-ZIP64
		///   limit is exceeded.
		/// </para>
		///
		/// <para>
		///   You may set the property at any time before calling Save().
		/// </para>
		///
		/// <para>
		///   When reading a zip file via the <c>Zipfile.Read()</c> method, DotNetZip
		///   will properly read ZIP64-endowed zip archives, regardless of the value of
		///   this property.  DotNetZip will always read ZIP64 archives.  This property
		///   governs only whether DotNetZip will write them. Therefore, when updating
		///   archives, be careful about setting this property after reading an archive
		///   that may use ZIP64 extensions.
		/// </para>
		///
		/// <para>
		///   An interesting question is, if you have set this property to
		///   <c>AsNecessary</c>, and then successfully saved, does the resulting
		///   archive use ZIP64 extensions or not?  To learn this, check the <see
		///   cref="OutputUsedZip64"/> property, after calling <c>Save()</c>.
		/// </para>
		///
		/// <para>
		///   Have you thought about
		///   <see href="http://cheeso.members.winisp.net/DotNetZipDonate.aspx">donating</see>?
		/// </para>
		///
		/// </remarks>
		/// <seealso cref="RequiresZip64"/>
		public Zip64Option UseZip64WhenSaving
		{
			get
			{
				return _zip64;
			}
			set
			{
				_zip64 = value;
			}
		}



		/// <summary>
		///   Indicates whether the archive requires ZIP64 extensions.
		/// </summary>
		///
		/// <remarks>
		///
		/// <para>
		///   This property is <c>null</c> (or <c>Nothing</c> in VB) if the archive has
		///   not been saved, and there are fewer than 65334 <c>ZipEntry</c> items
		///   contained in the archive.
		/// </para>
		///
		/// <para>
		///   The <c>Value</c> is true if any of the following four conditions holds:
		///   the uncompressed size of any entry is larger than 0xFFFFFFFF; the
		///   compressed size of any entry is larger than 0xFFFFFFFF; the relative
		///   offset of any entry within the zip archive is larger than 0xFFFFFFFF; or
		///   there are more than 65534 entries in the archive.  (0xFFFFFFFF =
		///   4,294,967,295).  The result may not be known until a <c>Save()</c> is attempted
		///   on the zip archive.  The Value of this <see cref="System.Nullable"/>
		///   property may be set only AFTER one of the Save() methods has been called.
		/// </para>
		///
		/// <para>
		///   If none of the four conditions holds, and the archive has been saved, then
		///   the <c>Value</c> is false.
		/// </para>
		///
		/// <para>
		///   A <c>Value</c> of false does not indicate that the zip archive, as saved,
		///   does not use ZIP64.  It merely indicates that ZIP64 is not required.  An
		///   archive may use ZIP64 even when not required if the <see
		///   cref="ZipFile.UseZip64WhenSaving"/> property is set to <see
		///   cref="Zip64Option.Always"/>, or if the <see
		///   cref="ZipFile.UseZip64WhenSaving"/> property is set to <see
		///   cref="Zip64Option.AsNecessary"/> and the output stream was not
		///   seekable. Use the <see cref="OutputUsedZip64"/> property to determine if
		///   the most recent <c>Save()</c> method resulted in an archive that utilized
		///   the ZIP64 extensions.
		/// </para>
		///
		/// </remarks>
		/// <seealso cref="UseZip64WhenSaving"/>
		/// <seealso cref="OutputUsedZip64"/>
		public Nullable<bool> RequiresZip64
		{
			get
			{
				if (_entries.Count > 65534)
					return new Nullable<bool>(true);

				// If the <c>ZipFile</c> has not been saved or if the contents have changed, then
				// it is not known if ZIP64 is required.
				if (!_hasBeenSaved || _contentsChanged) return null;

				// Whether ZIP64 is required is knowable.
				foreach (ZipEntry e in _entries.Values)
				{
					if (e.RequiresZip64.Value) return new Nullable<bool>(true);
				}

				return new Nullable<bool>(false);
			}
		}


		/// <summary>
		///   Indicates whether the most recent <c>Save()</c> operation used ZIP64 extensions.
		/// </summary>
		///
		/// <remarks>
		/// <para>
		///   The use of ZIP64 extensions within an archive is not always necessary, and
		///   for interoperability concerns, it may be desired to NOT use ZIP64 if
		///   possible.  The <see cref="ZipFile.UseZip64WhenSaving"/> property can be
		///   set to use ZIP64 extensions only when necessary.  In those cases,
		///   Sometimes applications want to know whether a Save() actually used ZIP64
		///   extensions.  Applications can query this read-only property to learn
		///   whether ZIP64 has been used in a just-saved <c>ZipFile</c>.
		/// </para>
		///
		/// <para>
		///   The value is <c>null</c> (or <c>Nothing</c> in VB) if the archive has not
		///   been saved.
		/// </para>
		///
		/// <para>
		///   Non-null values (<c>HasValue</c> is true) indicate whether ZIP64
		///   extensions were used during the most recent <c>Save()</c> operation.  The
		///   ZIP64 extensions may have been used as required by any particular entry
		///   because of its uncompressed or compressed size, or because the archive is
		///   larger than 4294967295 bytes, or because there are more than 65534 entries
		///   in the archive, or because the <c>UseZip64WhenSaving</c> property was set
		///   to <see cref="Zip64Option.Always"/>, or because the
		///   <c>UseZip64WhenSaving</c> property was set to <see
		///   cref="Zip64Option.AsNecessary"/> and the output stream was not seekable.
		///   The value of this property does not indicate the reason the ZIP64
		///   extensions were used.
		/// </para>
		///
		/// </remarks>
		/// <seealso cref="UseZip64WhenSaving"/>
		/// <seealso cref="RequiresZip64"/>
		public Nullable<bool> OutputUsedZip64
		{
			get
			{
				return _OutputUsesZip64;
			}
		}


		/// <summary>
		///   Indicates whether the most recent <c>Read()</c> operation read a zip file that uses
		///   ZIP64 extensions.
		/// </summary>
		///
		/// <remarks>
		///   This property will return null (Nothing in VB) if you've added an entry after reading
		///   the zip file.
		/// </remarks>
		public Nullable<bool> InputUsesZip64
		{
			get
			{
				if (_entries.Count > 65534)
					return true;

				foreach (ZipEntry e in this)
				{
					// if any entry was added after reading the zip file, then the result is null
					if (e.Source != ZipEntrySource.ZipFile) return null;

					// if any entry read from the zip used zip64, then the result is true
					if (e._InputUsesZip64) return true;
				}
				return false;
			}
		}


		/// <summary>
		///   The text encoding to use when writing new entries to the <c>ZipFile</c>,
		///   for those entries that cannot be encoded with the default (IBM437)
		///   encoding; or, the text encoding that was used when reading the entries
		///   from the <c>ZipFile</c>.
		/// </summary>
		///
		/// <remarks>
		/// <para>
		///   In <see href="http://www.pkware.com/documents/casestudies/APPNOTE.TXT">its
		///   zip specification</see>, PKWare describes two options for encoding
		///   filenames and comments: using IBM437 or UTF-8.  But, some archiving tools
		///   or libraries do not follow the specification, and instead encode
		///   characters using the system default code page.  For example, WinRAR when
		///   run on a machine in Shanghai may encode filenames with the Big-5 Chinese
		///   (950) code page.  This behavior is contrary to the Zip specification, but
		///   it occurs anyway.
		/// </para>
		///
		/// <para>
		///   When using DotNetZip to write zip archives that will be read by one of
		///   these other archivers, set this property to specify the code page to use
		///   when encoding the <see cref="ZipEntry.FileName"/> and <see
		///   cref="ZipEntry.Comment"/> for each <c>ZipEntry</c> in the zip file, for
		///   values that cannot be encoded with the default codepage for zip files,
		///   IBM437.  This is why this property is "provisional".  In all cases, IBM437
		///   is used where possible, in other words, where no loss of data would
		///   result. It is possible, therefore, to have a given entry with a
		///   <c>Comment</c> encoded in IBM437 and a <c>FileName</c> encoded with the
		///   specified "provisional" codepage.
		/// </para>
		///
		/// <para>
		///   Be aware that a zip file created after you've explicitly set the <see
		///   cref="ProvisionalAlternateEncoding" /> property to a value other than
		///   IBM437 may not be compliant to the PKWare specification, and may not be
		///   readable by compliant archivers.  On the other hand, many (most?)
		///   archivers are non-compliant and can read zip files created in arbitrary
		///   code pages.  The trick is to use or specify the proper codepage when
		///   reading the zip.
		/// </para>
		///
		/// <para>
		///   When creating a zip archive using this library, it is possible to change
		///   the value of <see cref="ProvisionalAlternateEncoding" /> between each
		///   entry you add, and between adding entries and the call to
		///   <c>Save()</c>. Don't do this. It will likely result in a zipfile that is
		///   not readable.  For best interoperability, either leave <see
		///   cref="ProvisionalAlternateEncoding" /> alone, or specify it only once,
		///   before adding any entries to the <c>ZipFile</c> instance.  There is one
		///   exception to this recommendation, described later.
		/// </para>
		///
		/// <para>
		///   When using an arbitrary, non-UTF8 code page for encoding, there is no
		///   standard way for the creator application - whether DotNetZip, WinZip,
		///   WinRar, or something else - to formally specify in the zip file which
		///   codepage has been used for the entries. As a result, readers of zip files
		///   are not able to inspect the zip file and determine the codepage that was
		///   used for the entries contained within it.  It is left to the application
		///   or user to determine the necessary codepage when reading zip files encoded
		///   this way.  In other words, if you explicitly specify the codepage when you
		///   create the zipfile, you must explicitly specify the same codepage when
		///   reading the zipfile.
		/// </para>
		///
		/// <para>
		///   The way you specify the code page to use when reading a zip file varies
		///   depending on the tool or library you use to read the zip.  In DotNetZip,
		///   you use a ZipFile.Read() method that accepts an encoding parameter.  It
		///   isn't possible with Windows Explorer, as far as I know, to specify an
		///   explicit codepage to use when reading a zip.  If you use an incorrect
		///   codepage when reading a zipfile, you will get entries with filenames that
		///   are incorrect, and the incorrect filenames may even contain characters
		///   that are not legal for use within filenames in Windows. Extracting entries
		///   with illegal characters in the filenames will lead to exceptions. It's too
		///   bad, but this is just the way things are with code pages in zip
		///   files. Caveat Emptor.
		/// </para>
		///
		/// <para>
		///   Example: Suppose you create a zipfile that contains entries with
		///   filenames that have Danish characters.  If you use <see
		///   cref="ProvisionalAlternateEncoding" /> equal to "iso-8859-1" (cp 28591),
		///   the filenames will be correctly encoded in the zip.  But, to read that
		///   zipfile correctly, you have to specify the same codepage at the time you
		///   read it. If try to read that zip file with Windows Explorer or another
		///   application that is not flexible with respect to the codepage used to
		///   decode filenames in zipfiles, you will get a filename like "Inf?txt".
		/// </para>
		///
		/// <para>
		///   When using DotNetZip to read a zip archive, and the zip archive uses an
		///   arbitrary code page, you must specify the encoding to use before or when
		///   the <c>Zipfile</c> is READ.  This means you must use a <c>ZipFile.Read()</c>
		///   method that allows you to specify a System.Text.Encoding parameter.  Setting
		///   the ProvisionalAlternateEncoding property after your application has read in
		///   the zip archive will not affect the entry names of entries that have already
		///   been read in.
		/// </para>
		///
		/// <para>
		///   And now, the exception to the rule described above.  One strategy for
		///   specifying the code page for a given zip file is to describe the code page
		///   in a human-readable form in the Zip comment. For example, the comment may
		///   read "Entries in this archive are encoded in the Big5 code page".  For
		///   maximum interoperability, the zip comment in this case should be encoded
		///   in the default, IBM437 code page.  In this case, the zip comment is
		///   encoded using a different page than the filenames.  To do this, Specify
		///   <c>ProvisionalAlternateEncoding</c> to your desired region-specific code
		///   page, once before adding any entries, and then reset
		///   <c>ProvisionalAlternateEncoding</c> to IBM437 before setting the <see
		///   cref="Comment"/> property and calling Save().
		/// </para>
		/// </remarks>
		///
		/// <example>
		/// This example shows how to read a zip file using the Big-5 Chinese code page
		/// (950), and extract each entry in the zip file.  For this code to work as
		/// desired, the <c>Zipfile</c> must have been created using the big5 code page
		/// (CP950). This is typical, for example, when using WinRar on a machine with
		/// CP950 set as the default code page.  In that case, the names of entries
		/// within the Zip archive will be stored in that code page, and reading the zip
		/// archive must be done using that code page.  If the application did not use
		/// the correct code page in <c>ZipFile.Read()</c>, then names of entries within the
		/// zip archive would not be correctly retrieved.
		/// <code>
		/// using (var zip = ZipFile.Read(zipFileName, System.Text.Encoding.GetEncoding("big5")))
		/// {
		///     // retrieve and extract an entry using a name encoded with CP950
		///     zip[MyDesiredEntry].Extract("unpack");
		/// }
		/// </code>
		///
		/// <code lang="VB">
		/// Using zip As ZipFile = ZipFile.Read(ZipToExtract, System.Text.Encoding.GetEncoding("big5"))
		///     ' retrieve and extract an entry using a name encoded with CP950
		///     zip(MyDesiredEntry).Extract("unpack")
		/// End Using
		/// </code>
		/// </example>
		///
		/// <seealso cref="PickGold.Zip.ZipFile.DefaultEncoding">DefaultEncoding</seealso>
		[Obsolete("use AlternateEncoding instead.")]
		public System.Text.Encoding ProvisionalAlternateEncoding
		{
			get
			{
				if (_alternateEncodingUsage == ZipOption.AsNecessary)
					return _alternateEncoding;
				return null;
			}
			set
			{
				_alternateEncoding = value;
				_alternateEncodingUsage = ZipOption.AsNecessary;
			}
		}


		/// <summary>
		///   A Text Encoding to use when encoding the filenames and comments for
		///   all the ZipEntry items, during a ZipFile.Save() operation.
		/// </summary>
		/// <remarks>
		///   <para>
		///     Whether the encoding specified here is used during the save depends
		///     on <see cref="AlternateEncodingUsage"/>.
		///   </para>
		/// </remarks>
		public System.Text.Encoding AlternateEncoding
		{
			get
			{
				return _alternateEncoding;
			}
			set
			{
				_alternateEncoding = value;
			}
		}


		/// <summary>
		///   A flag that tells if and when this instance should apply
		///   AlternateEncoding to encode the filenames and comments associated to
		///   of ZipEntry objects contained within this instance.
		/// </summary>
		public ZipOption AlternateEncodingUsage
		{
			get
			{
				return _alternateEncodingUsage;
			}
			set
			{
				_alternateEncodingUsage = value;
			}
		}


		/// <summary>
		/// The default text encoding used in zip archives.  It is numeric 437, also
		/// known as IBM437.
		/// </summary>
		/// <seealso cref="PickGold.Zip.ZipFile.ProvisionalAlternateEncoding"/>
		public static System.Text.Encoding DefaultEncoding
		{
			get
			{
				return _defaultEncoding;
			}
		}


		/// <summary>
		/// Gets or sets the <c>TextWriter</c> to which status messages are delivered
		/// for the instance.
		/// </summary>
		///
		/// <remarks>
		///   If the TextWriter is set to a non-null value, then verbose output is sent
		///   to the <c>TextWriter</c> during <c>Add</c><c>, Read</c><c>, Save</c> and
		///   <c>Extract</c> operations.  Typically, console applications might use
		///   <c>Console.Out</c> and graphical or headless applications might use a
		///   <c>System.IO.StringWriter</c>. The output of this is suitable for viewing
		///   by humans.
		/// </remarks>
		///
		/// <example>
		/// <para>
		///   In this example, a console application instantiates a <c>ZipFile</c>, then
		///   sets the <c>StatusMessageTextWriter</c> to <c>Console.Out</c>.  At that
		///   point, all verbose status messages for that <c>ZipFile</c> are sent to the
		///   console.
		/// </para>
		///
		/// <code lang="C#">
		/// using (ZipFile zip= ZipFile.Read(FilePath))
		/// {
		///   zip.StatusMessageTextWriter= System.Console.Out;
		///   // messages are sent to the console during extraction
		///   zip.ExtractAll();
		/// }
		/// </code>
		///
		/// <code lang="VB">
		/// Using zip As ZipFile = ZipFile.Read(FilePath)
		///   zip.StatusMessageTextWriter= System.Console.Out
		///   'Status Messages will be sent to the console during extraction
		///   zip.ExtractAll()
		/// End Using
		/// </code>
		///
		/// <para>
		///   In this example, a Windows Forms application instantiates a
		///   <c>ZipFile</c>, then sets the <c>StatusMessageTextWriter</c> to a
		///   <c>StringWriter</c>.  At that point, all verbose status messages for that
		///   <c>ZipFile</c> are sent to the <c>StringWriter</c>.
		/// </para>
		///
		/// <code lang="C#">
		/// var sw = new System.IO.StringWriter();
		/// using (ZipFile zip= ZipFile.Read(FilePath))
		/// {
		///   zip.StatusMessageTextWriter= sw;
		///   zip.ExtractAll();
		/// }
		/// Console.WriteLine("{0}", sw.ToString());
		/// </code>
		///
		/// <code lang="VB">
		/// Dim sw as New System.IO.StringWriter
		/// Using zip As ZipFile = ZipFile.Read(FilePath)
		///   zip.StatusMessageTextWriter= sw
		///   zip.ExtractAll()
		/// End Using
		/// 'Status Messages are now available in sw
		///
		/// </code>
		/// </example>
		public TextWriter StatusMessageTextWriter
		{
			get { return _StatusMessageTextWriter; }
			set { _StatusMessageTextWriter = value; }
		}




		/// <summary>
		///   Gets or sets the name for the folder to store the temporary file
		///   this library writes when saving a zip archive.
		/// </summary>
		///
		/// <remarks>
		/// <para>
		///   This library will create a temporary file when saving a Zip archive to a
		///   file.  This file is written when calling one of the <c>Save()</c> methods
		///   that does not save to a stream, or one of the <c>SaveSelfExtractor()</c>
		///   methods.
		/// </para>
		///
		/// <para>
		///   By default, the library will create the temporary file in the directory
		///   specified for the file itself, via the <see cref="Name"/> property or via
		///   the <see cref="ZipFile.Save(String)"/> method.
		/// </para>
		///
		/// <para>
		///   Setting this property allows applications to override this default
		///   behavior, so that the library will create the temporary file in the
		///   specified folder. For example, to have the library create the temporary
		///   file in the current working directory, regardless where the <c>ZipFile</c>
		///   is saved, specfy ".".  To revert to the default behavior, set this
		///   property to <c>null</c> (<c>Nothing</c> in VB).
		/// </para>
		///
		/// <para>
		///   When setting the property to a non-null value, the folder specified must
		///   exist; if it does not an exception is thrown.  The application should have
		///   write and delete permissions on the folder.  The permissions are not
		///   explicitly checked ahead of time; if the application does not have the
		///   appropriate rights, an exception will be thrown at the time <c>Save()</c>
		///   is called.
		/// </para>
		///
		/// <para>
		///   There is no temporary file created when reading a zip archive.  When
		///   saving to a Stream, there is no temporary file created.  For example, if
		///   the application is an ASP.NET application and calls <c>Save()</c>
		///   specifying the <c>Response.OutputStream</c> as the output stream, there is
		///   no temporary file created.
		/// </para>
		/// </remarks>
		///
		/// <exception cref="System.IO.FileNotFoundException">
		/// Thrown when setting the property if the directory does not exist.
		/// </exception>
		///
		public String TempFileFolder
		{
			get { return _TempFileFolder; }

			set
			{
				_TempFileFolder = value;
				if (value == null) return;

				if (!Directory.Exists(value))
					throw new FileNotFoundException(String.Format("That directory ({0}) does not exist.", value));

			}
		}

		/// <summary>
		/// Sets the password to be used on the <c>ZipFile</c> instance.
		/// </summary>
		///
		/// <remarks>
		///
		/// <para>
		///   When writing a zip archive, this password is applied to the entries, not
		///   to the zip archive itself. It applies to any <c>ZipEntry</c> subsequently
		///   added to the <c>ZipFile</c>, using one of the <c>AddFile</c>,
		///   <c>AddDirectory</c>, <c>AddEntry</c>, or <c>AddItem</c> methods, etc.
		///   When reading a zip archive, this property applies to any entry
		///   subsequently extracted from the <c>ZipFile</c> using one of the Extract
		///   methods on the <c>ZipFile</c> class.
		/// </para>
		///
		/// <para>
		///   When writing a zip archive, keep this in mind: though the password is set
		///   on the ZipFile object, according to the Zip spec, the "directory" of the
		///   archive - in other words the list of entries or files contained in the archive - is
		///   not encrypted with the password, or protected in any way.  If you set the
		///   Password property, the password actually applies to individual entries
		///   that are added to the archive, subsequent to the setting of this property.
		///   The list of filenames in the archive that is eventually created will
		///   appear in clear text, but the contents of the individual files are
		///   encrypted.  This is how Zip encryption works.
		/// </para>
		///
		/// <para>
		///   One simple way around this limitation is to simply double-wrap sensitive
		///   filenames: Store the files in a zip file, and then store that zip file
		///   within a second, "outer" zip file.  If you apply a password to the outer
		///   zip file, then readers will be able to see that the outer zip file
		///   contains an inner zip file.  But readers will not be able to read the
		///   directory or file list of the inner zip file.
		/// </para>
		///
		/// <para>
		///   If you set the password on the <c>ZipFile</c>, and then add a set of files
		///   to the archive, then each entry is encrypted with that password.  You may
		///   also want to change the password between adding different entries. If you
		///   set the password, add an entry, then set the password to <c>null</c>
		///   (<c>Nothing</c> in VB), and add another entry, the first entry is
		///   encrypted and the second is not.  If you call <c>AddFile()</c>, then set
		///   the <c>Password</c> property, then call <c>ZipFile.Save</c>, the file
		///   added will not be password-protected, and no warning will be generated.
		/// </para>
		///
		/// <para>
		///   When setting the Password, you may also want to explicitly set the <see
		///   cref="Encryption"/> property, to specify how to encrypt the entries added
		///   to the ZipFile.  If you set the Password to a non-null value and do not
		///   set <see cref="Encryption"/>, then PKZip 2.0 ("Weak") encryption is used.
		///   This encryption is relatively weak but is very interoperable. If you set
		///   the password to a <c>null</c> value (<c>Nothing</c> in VB), Encryption is
		///   reset to None.
		/// </para>
		///
		/// <para>
		///   All of the preceding applies to writing zip archives, in other words when
		///   you use one of the Save methods.  To use this property when reading or an
		///   existing ZipFile, do the following: set the Password property on the
		///   <c>ZipFile</c>, then call one of the Extract() overloads on the <see
		///   cref="ZipEntry" />. In this case, the entry is extracted using the
		///   <c>Password</c> that is specified on the <c>ZipFile</c> instance. If you
		///   have not set the <c>Password</c> property, then the password is
		///   <c>null</c>, and the entry is extracted with no password.
		/// </para>
		///
		/// <para>
		///   If you set the Password property on the <c>ZipFile</c>, then call
		///   <c>Extract()</c> an entry that has not been encrypted with a password, the
		///   password is not used for that entry, and the <c>ZipEntry</c> is extracted
		///   as normal. In other words, the password is used only if necessary.
		/// </para>
		///
		/// <para>
		///   The <see cref="ZipEntry"/> class also has a <see
		///   cref="ZipEntry.Password">Password</see> property.  It takes precedence
		///   over this property on the <c>ZipFile</c>.  Typically, you would use the
		///   per-entry Password when most entries in the zip archive use one password,
		///   and a few entries use a different password.  If all entries in the zip
		///   file use the same password, then it is simpler to just set this property
		///   on the <c>ZipFile</c> itself, whether creating a zip archive or extracting
		///   a zip archive.
		/// </para>
		///
		/// </remarks>
		///
		/// <example>
		/// <para>
		///   This example creates a zip file, using password protection for the
		///   entries, and then extracts the entries from the zip file.  When creating
		///   the zip file, the Readme.txt file is not protected with a password, but
		///   the other two are password-protected as they are saved. During extraction,
		///   each file is extracted with the appropriate password.
		/// </para>
		/// <code>
		/// // create a file with encryption
		/// using (ZipFile zip = new ZipFile())
		/// {
		///     zip.AddFile("ReadMe.txt");
		///     zip.Password= "!Secret1";
		///     zip.AddFile("MapToTheSite-7440-N49th.png");
		///     zip.AddFile("2008-Regional-Sales-Report.pdf");
		///     zip.Save("EncryptedArchive.zip");
		/// }
		///
		/// // extract entries that use encryption
		/// using (ZipFile zip = ZipFile.Read("EncryptedArchive.zip"))
		/// {
		///     zip.Password= "!Secret1";
		///     zip.ExtractAll("extractDir");
		/// }
		///
		/// </code>
		///
		/// <code lang="VB">
		/// Using zip As New ZipFile
		///     zip.AddFile("ReadMe.txt")
		///     zip.Password = "123456!"
		///     zip.AddFile("MapToTheSite-7440-N49th.png")
		///     zip.Password= "!Secret1";
		///     zip.AddFile("2008-Regional-Sales-Report.pdf")
		///     zip.Save("EncryptedArchive.zip")
		/// End Using
		///
		///
		/// ' extract entries that use encryption
		/// Using (zip as ZipFile = ZipFile.Read("EncryptedArchive.zip"))
		///     zip.Password= "!Secret1"
		///     zip.ExtractAll("extractDir")
		/// End Using
		///
		/// </code>
		///
		/// </example>
		///
		/// <seealso cref="PickGold.Zip.ZipFile.Encryption">ZipFile.Encryption</seealso>
		/// <seealso cref="PickGold.Zip.ZipEntry.Password">ZipEntry.Password</seealso>
		public String Password
		{
			set
			{
				_Password = value;
				if (_Password == null)
				{
					Encryption = EncryptionAlgorithm.None;
				}
				else if (Encryption == EncryptionAlgorithm.None)
				{
					Encryption = EncryptionAlgorithm.PkzipWeak;
				}
			}
			private get
			{
				return _Password;
			}
		}





		/// <summary>
		///   The action the library should take when extracting a file that already
		///   exists.
		/// </summary>
		///
		/// <remarks>
		/// <para>
		///   This property affects the behavior of the Extract methods (one of the
		///   <c>Extract()</c> or <c>ExtractWithPassword()</c> overloads), when
		///   extraction would would overwrite an existing filesystem file. If you do
		///   not set this property, the library throws an exception when extracting an
		///   entry would overwrite an existing file.
		/// </para>
		///
		/// <para>
		///   This property has no effect when extracting to a stream, or when the file
		///   to be extracted does not already exist.
		/// </para>
		/// </remarks>
		/// <seealso cref="PickGold.Zip.ZipEntry.ExtractExistingFile"/>
		public ExtractExistingFileAction ExtractExistingFile
		{
			get;
			set;
		}


		/// <summary>
		///   The action the library should take when an error is encountered while
		///   opening or reading files as they are saved into a zip archive.
		/// </summary>
		///
		/// <remarks>
		///  <para>
		///    Errors can occur as a file is being saved to the zip archive.  For
		///    example, the File.Open may fail, or a File.Read may fail, because of
		///    lock conflicts or other reasons.
		///  </para>
		///
		///  <para>
		///    The first problem might occur after having called AddDirectory() on a
		///    directory that contains a Clipper .dbf file; the file is locked by
		///    Clipper and cannot be opened for read by another process. An example of
		///    the second problem might occur when trying to zip a .pst file that is in
		///    use by Microsoft Outlook. Outlook locks a range on the file, which allows
		///    other processes to open the file, but not read it in its entirety.
		///  </para>
		///
		///  <para>
		///    This property tells DotNetZip what you would like to do in the case of
		///    these errors.  The primary options are: <c>ZipErrorAction.Throw</c> to
		///    throw an exception (this is the default behavior if you don't set this
		///    property); <c>ZipErrorAction.Skip</c> to Skip the file for which there
		///    was an error and continue saving; <c>ZipErrorAction.Retry</c> to Retry
		///    the entry that caused the problem; or
		///    <c>ZipErrorAction.InvokeErrorEvent</c> to invoke an event handler.
		///  </para>
		///
		///  <para>
		///    This property is implicitly set to <c>ZipErrorAction.InvokeErrorEvent</c>
		///    if you add a handler to the <see cref="ZipError" /> event.  If you set
		///    this property to something other than
		///    <c>ZipErrorAction.InvokeErrorEvent</c>, then the <c>ZipError</c>
		///    event is implicitly cleared.  What it means is you can set one or the
		///    other (or neither), depending on what you want, but you never need to set
		///    both.
		///  </para>
		///
		///  <para>
		///    As with some other properties on the <c>ZipFile</c> class, like <see
		///    cref="Password"/>, <see cref="Encryption"/>, and <see
		///    cref="CompressionLevel"/>, setting this property on a <c>ZipFile</c>
		///    instance will cause the specified <c>ZipErrorAction</c> to be used on all
		///    <see cref="ZipEntry"/> items that are subsequently added to the
		///    <c>ZipFile</c> instance. If you set this property after you have added
		///    items to the <c>ZipFile</c>, but before you have called <c>Save()</c>,
		///    those items will not use the specified error handling action.
		///  </para>
		///
		///  <para>
		///    If you want to handle any errors that occur with any entry in the zip
		///    file in the same way, then set this property once, before adding any
		///    entries to the zip archive.
		///  </para>
		///
		///  <para>
		///    If you set this property to <c>ZipErrorAction.Skip</c> and you'd like to
		///    learn which files may have been skipped after a <c>Save()</c>, you can
		///    set the <see cref="StatusMessageTextWriter" /> on the ZipFile before
		///    calling <c>Save()</c>. A message will be emitted into that writer for
		///    each skipped file, if any.
		///  </para>
		///
		/// </remarks>
		///
		/// <example>
		///   This example shows how to tell DotNetZip to skip any files for which an
		///   error is generated during the Save().
		/// <code lang="VB">
		/// Public Sub SaveZipFile()
		///     Dim SourceFolder As String = "fodder"
		///     Dim DestFile As String =  "eHandler.zip"
		///     Dim sw as New StringWriter
		///     Using zipArchive As ZipFile = New ZipFile
		///         ' Tell DotNetZip to skip any files for which it encounters an error
		///         zipArchive.ZipErrorAction = ZipErrorAction.Skip
		///         zipArchive.StatusMessageTextWriter = sw
		///         zipArchive.AddDirectory(SourceFolder)
		///         zipArchive.Save(DestFile)
		///     End Using
		///     ' examine sw here to see any messages
		/// End Sub
		///
		/// </code>
		/// </example>
		///
		/// <seealso cref="PickGold.Zip.ZipEntry.ZipErrorAction"/>
		/// <seealso cref="PickGold.Zip.ZipFile.ZipError"/>

		public ZipErrorAction ZipErrorAction
		{
			get
			{
				if (ZipError != null)
					_zipErrorAction = ZipErrorAction.InvokeErrorEvent;
				return _zipErrorAction;
			}
			set
			{
				_zipErrorAction = value;
				if (_zipErrorAction != ZipErrorAction.InvokeErrorEvent && ZipError != null)
					ZipError = null;
			}
		}


		/// <summary>
		///   The Encryption to use for entries added to the <c>ZipFile</c>.
		/// </summary>
		///
		/// <remarks>
		/// <para>
		///   Set this when creating a zip archive, or when updating a zip archive. The
		///   specified Encryption is applied to the entries subsequently added to the
		///   <c>ZipFile</c> instance.  Applications do not need to set the
		///   <c>Encryption</c> property when reading or extracting a zip archive.
		/// </para>
		///
		/// <para>
		///   If you set this to something other than EncryptionAlgorithm.None, you
		///   will also need to set the <see cref="Password"/>.
		/// </para>
		///
		/// <para>
		///   As with some other properties on the <c>ZipFile</c> class, like <see
		///   cref="Password"/> and <see cref="CompressionLevel"/>, setting this
		///   property on a <c>ZipFile</c> instance will cause the specified
		///   <c>EncryptionAlgorithm</c> to be used on all <see cref="ZipEntry"/> items
		///   that are subsequently added to the <c>ZipFile</c> instance. In other
		///   words, if you set this property after you have added items to the
		///   <c>ZipFile</c>, but before you have called <c>Save()</c>, those items will
		///   not be encrypted or protected with a password in the resulting zip
		///   archive. To get a zip archive with encrypted entries, set this property,
		///   along with the <see cref="Password"/> property, before calling
		///   <c>AddFile</c>, <c>AddItem</c>, or <c>AddDirectory</c> (etc.) on the
		///   <c>ZipFile</c> instance.
		/// </para>
		///
		/// <para>
		///   If you read a <c>ZipFile</c>, you can modify the <c>Encryption</c> on an
		///   encrypted entry, only by setting the <c>Encryption</c> property on the
		///   <c>ZipEntry</c> itself.  Setting the <c>Encryption</c> property on the
		///   <c>ZipFile</c>, once it has been created via a call to
		///   <c>ZipFile.Read()</c>, does not affect entries that were previously read.
		/// </para>
		///
		/// <para>
		///   For example, suppose you read a <c>ZipFile</c>, and there is an encrypted
		///   entry.  Setting the <c>Encryption</c> property on that <c>ZipFile</c> and
		///   then calling <c>Save()</c> on the <c>ZipFile</c> does not update the
		///   <c>Encryption</c> used for the entries in the archive.  Neither is an
		///   exception thrown. Instead, what happens during the <c>Save()</c> is that
		///   all previously existing entries are copied through to the new zip archive,
		///   with whatever encryption and password that was used when originally
		///   creating the zip archive. Upon re-reading that archive, to extract
		///   entries, applications should use the original password or passwords, if
		///   any.
		/// </para>
		///
		/// <para>
		///   Suppose an application reads a <c>ZipFile</c>, and there is an encrypted
		///   entry.  Setting the <c>Encryption</c> property on that <c>ZipFile</c> and
		///   then adding new entries (via <c>AddFile()</c>, <c>AddEntry()</c>, etc)
		///   and then calling <c>Save()</c> on the <c>ZipFile</c> does not update the
		///   <c>Encryption</c> on any of the entries that had previously been in the
		///   <c>ZipFile</c>.  The <c>Encryption</c> property applies only to the
		///   newly-added entries.
		/// </para>
		///
		/// </remarks>
		///
		/// <example>
		/// <para>
		///   This example creates a zip archive that uses encryption, and then extracts
		///   entries from the archive.  When creating the zip archive, the ReadMe.txt
		///   file is zipped without using a password or encryption.  The other files
		///   use encryption.
		/// </para>
		///
		/// <code>
		/// // Create a zip archive with AES Encryption.
		/// using (ZipFile zip = new ZipFile())
		/// {
		///     zip.AddFile("ReadMe.txt");
		///     zip.Encryption= EncryptionAlgorithm.WinZipAes256;
		///     zip.Password= "Top.Secret.No.Peeking!";
		///     zip.AddFile("7440-N49th.png");
		///     zip.AddFile("2008-Regional-Sales-Report.pdf");
		///     zip.Save("EncryptedArchive.zip");
		/// }
		///
		/// // Extract a zip archive that uses AES Encryption.
		/// // You do not need to specify the algorithm during extraction.
		/// using (ZipFile zip = ZipFile.Read("EncryptedArchive.zip"))
		/// {
		///     zip.Password= "Top.Secret.No.Peeking!";
		///     zip.ExtractAll("extractDirectory");
		/// }
		/// </code>
		///
		/// <code lang="VB">
		/// ' Create a zip that uses Encryption.
		/// Using zip As New ZipFile()
		///     zip.Encryption= EncryptionAlgorithm.WinZipAes256
		///     zip.Password= "Top.Secret.No.Peeking!"
		///     zip.AddFile("ReadMe.txt")
		///     zip.AddFile("7440-N49th.png")
		///     zip.AddFile("2008-Regional-Sales-Report.pdf")
		///     zip.Save("EncryptedArchive.zip")
		/// End Using
		///
		/// ' Extract a zip archive that uses AES Encryption.
		/// ' You do not need to specify the algorithm during extraction.
		/// Using (zip as ZipFile = ZipFile.Read("EncryptedArchive.zip"))
		///     zip.Password= "Top.Secret.No.Peeking!"
		///     zip.ExtractAll("extractDirectory")
		/// End Using
		/// </code>
		///
		/// </example>
		///
		/// <seealso cref="PickGold.Zip.ZipFile.Password">ZipFile.Password</seealso>
		/// <seealso cref="PickGold.Zip.ZipEntry.Encryption">ZipEntry.Encryption</seealso>
		public EncryptionAlgorithm Encryption
		{
			get
			{
				return _Encryption;
			}
			set
			{
				if (value == EncryptionAlgorithm.Unsupported)
					throw new InvalidOperationException("You may not set Encryption to that value.");
				_Encryption = value;
			}
		}



		/// <summary>
		///   A callback that allows the application to specify the compression level
		///   to use for entries subsequently added to the zip archive.
		/// </summary>
		///
		/// <remarks>
		///
		/// <para>
		///   With this callback, the DotNetZip library allows the application to
		///   determine whether compression will be used, at the time of the
		///   <c>Save</c>. This may be useful if the application wants to favor
		///   speed over size, and wants to defer the decision until the time of
		///   <c>Save</c>.
		/// </para>
		///
		/// <para>
		///   Typically applications set the <see cref="CompressionLevel"/> property on
		///   the <c>ZipFile</c> or on each <c>ZipEntry</c> to determine the level of
		///   compression used. This is done at the time the entry is added to the
		///   <c>ZipFile</c>. Setting the property to
		///   <c>PickGold.Zlib.CompressionLevel.None</c> means no compression will be used.
		/// </para>
		///
		/// <para>
		///   This callback allows the application to defer the decision on the
		///   <c>CompressionLevel</c> to use, until the time of the call to
		///   <c>ZipFile.Save()</c>. The callback is invoked once per <c>ZipEntry</c>,
		///   at the time the data for the entry is being written out as part of a
		///   <c>Save()</c> operation. The application can use whatever criteria it
		///   likes in determining the level to return.  For example, an application may
		///   wish that no .mp3 files should be compressed, because they are already
		///   compressed and the extra compression is not worth the CPU time incurred,
		///   and so can return <c>None</c> for all .mp3 entries.
		/// </para>
		///
		/// <para>
		///   The library determines whether compression will be attempted for an entry
		///   this way: If the entry is a zero length file, or a directory, no
		///   compression is used.  Otherwise, if this callback is set, it is invoked
		///   and the <c>CompressionLevel</c> is set to the return value. If this
		///   callback has not been set, then the previously set value for
		///   <c>CompressionLevel</c> is used.
		/// </para>
		///
		/// </remarks>
		public SetCompressionCallback SetCompression
		{
			get;
			set;
		}


		/// <summary>
		/// The maximum size of an output segment, when saving a split Zip file.
		/// </summary>
		/// <remarks>
		///   <para>
		///     Set this to a non-zero value before calling <see cref="Save()"/> or <see
		///     cref="Save(String)"/> to specify that the ZipFile should be saved as a
		///     split archive, also sometimes called a spanned archive. Some also
		///     call them multi-file archives.
		///   </para>
		///
		///   <para>
		///     A split zip archive is saved in a set of discrete filesystem files,
		///     rather than in a single file. This is handy when transmitting the
		///     archive in email or some other mechanism that has a limit to the size of
		///     each file.  The first file in a split archive will be named
		///     <c>basename.z01</c>, the second will be named <c>basename.z02</c>, and
		///     so on. The final file is named <c>basename.zip</c>. According to the zip
		///     specification from PKWare, the minimum value is 65536, for a 64k segment
		///     size. The maximum number of segments allows in a split archive is 99.
		///   </para>
		///
		///   <para>
		///     The value of this property determines the maximum size of a split
		///     segment when writing a split archive.  For example, suppose you have a
		///     <c>ZipFile</c> that would save to a single file of 200k. If you set the
		///     <c>MaxOutputSegmentSize</c> to 65536 before calling <c>Save()</c>, you
		///     will get four distinct output files. On the other hand if you set this
		///     property to 256k, then you will get a single-file archive for that
		///     <c>ZipFile</c>.
		///   </para>
		///
		///   <para>
		///     The size of each split output file will be as large as possible, up to
		///     the maximum size set here. The zip specification requires that some data
		///     fields in a zip archive may not span a split boundary, and an output
		///     segment may be smaller than the maximum if necessary to avoid that
		///     problem. Also, obviously the final segment of the archive may be smaller
		///     than the maximum segment size. Segments will never be larger than the
		///     value set with this property.
		///   </para>
		///
		///   <para>
		///     You can save a split Zip file only when saving to a regular filesystem
		///     file. It's not possible to save a split zip file as a self-extracting
		///     archive, nor is it possible to save a split zip file to a stream. When
		///     saving to a SFX or to a Stream, this property is ignored.
		///   </para>
		///
		///   <para>
		///     About interoperability: Split or spanned zip files produced by DotNetZip
		///     can be read by WinZip or PKZip, and vice-versa. Segmented zip files may
		///     not be readable by other tools, if those other tools don't support zip
		///     spanning or splitting.  When in doubt, test.  I don't believe Windows
		///     Explorer can extract a split archive.
		///   </para>
		///
		///   <para>
		///     This property has no effect when reading a split archive. You can read
		///     a split archive in the normal way with DotNetZip.
		///   </para>
		///
		///   <para>
		///     When saving a zip file, if you want a regular zip file rather than a
		///     split zip file, don't set this property, or set it to Zero.
		///   </para>
		///
		///   <para>
		///     If you read a split archive, with <see cref="ZipFile.Read(string)"/> and
		///     then subsequently call <c>ZipFile.Save()</c>, unless you set this
		///     property before calling <c>Save()</c>, you will get a normal,
		///     single-file archive.
		///   </para>
		/// </remarks>
		///
		/// <seealso cref="NumberOfSegmentsForMostRecentSave"/>
		public Int32 MaxOutputSegmentSize
		{
			get
			{
				return _maxOutputSegmentSize;
			}
			set
			{
				if (value < 65536 && value != 0)
					throw new ZipException("The minimum acceptable segment size is 65536.");
				_maxOutputSegmentSize = value;
			}
		}


		/// <summary>
		///   Returns the number of segments used in the most recent Save() operation.
		/// </summary>
		/// <remarks>
		///   <para>
		///     This is normally zero, unless you have set the <see
		///     cref="MaxOutputSegmentSize"/> property.  If you have set <see
		///     cref="MaxOutputSegmentSize"/>, and then you save a file, after the call to
		///     Save() completes, you can read this value to learn the number of segments that
		///     were created.
		///   </para>
		///   <para>
		///     If you call Save("Archive.zip"), and it creates 5 segments, then you
		///     will have filesystem files named Archive.z01, Archive.z02, Archive.z03,
		///     Archive.z04, and Archive.zip, and the value of this property will be 5.
		///   </para>
		/// </remarks>
		/// <seealso cref="MaxOutputSegmentSize"/>
		public Int32 NumberOfSegmentsForMostRecentSave
		{
			get
			{
				return unchecked((Int32)_numberOfSegmentsForMostRecentSave + 1);
			}
		}


#if !NETCF
		/// <summary>
		///   The size threshold for an entry, above which a parallel deflate is used.
		/// </summary>
		///
		/// <remarks>
		///
		///   <para>
		///     DotNetZip will use multiple threads to compress any ZipEntry,
		///     if the entry is larger than the given size.  Zero means "always
		///     use parallel deflate", while -1 means "never use parallel
		///     deflate". The default value for this property is 512k. Aside
		///     from the special values of 0 and 1, the minimum value is 65536.
		///   </para>
		///
		///   <para>
		///     If the entry size cannot be known before compression, as with a
		///     read-forward stream, then Parallel deflate will never be
		///     performed, unless the value of this property is zero.
		///   </para>
		///
		///   <para>
		///     A parallel deflate operations will speed up the compression of
		///     large files, on computers with multiple CPUs or multiple CPU
		///     cores.  For files above 1mb, on a dual core or dual-cpu (2p)
		///     machine, the time required to compress the file can be 70% of the
		///     single-threaded deflate.  For very large files on 4p machines the
		///     compression can be done in 30% of the normal time.  The downside
		///     is that parallel deflate consumes extra memory during the deflate,
		///     and the deflation is not as effective.
		///   </para>
		///
		///   <para>
		///     Parallel deflate tends to yield slightly less compression when
		///     compared to as single-threaded deflate; this is because the original
		///     data stream is split into multiple independent buffers, each of which
		///     is compressed in parallel.  But because they are treated
		///     independently, there is no opportunity to share compression
		///     dictionaries.  For that reason, a deflated stream may be slightly
		///     larger when compressed using parallel deflate, as compared to a
		///     traditional single-threaded deflate. Sometimes the increase over the
		///     normal deflate is as much as 5% of the total compressed size. For
		///     larger files it can be as small as 0.1%.
		///   </para>
		///
		///   <para>
		///     Multi-threaded compression does not give as much an advantage when
		///     using Encryption. This is primarily because encryption tends to slow
		///     down the entire pipeline. Also, multi-threaded compression gives less
		///     of an advantage when using lower compression levels, for example <see
		///     cref="PickGold.Zlib.CompressionLevel.BestSpeed"/>.  You may have to
		///     perform some tests to determine the best approach for your situation.
		///   </para>
		///
		/// </remarks>
		///
		/// <seealso cref="ParallelDeflateMaxBufferPairs"/>
		///
		public long ParallelDeflateThreshold
		{
			set
			{
				if ((value != 0) && (value != -1) && (value < 64 * 1024))
					throw new ArgumentOutOfRangeException("ParallelDeflateThreshold should be -1, 0, or > 65536");
				_ParallelDeflateThreshold = value;
			}
			get
			{
				return _ParallelDeflateThreshold;
			}
		}

		/// <summary>
		///   The maximum number of buffer pairs to use when performing
		///   parallel compression.
		/// </summary>
		///
		/// <remarks>
		/// <para>
		///   This property sets an upper limit on the number of memory
		///   buffer pairs to create when performing parallel
		///   compression.  The implementation of the parallel
		///   compression stream allocates multiple buffers to
		///   facilitate parallel compression.  As each buffer fills up,
		///   the stream uses <see
		///   cref="System.Threading.ThreadPool.QueueUserWorkItem(System.Threading.WaitCallback)">
		///   ThreadPool.QueueUserWorkItem()</see> to compress those
		///   buffers in a background threadpool thread. After a buffer
		///   is compressed, it is re-ordered and written to the output
		///   stream.
		/// </para>
		///
		/// <para>
		///   A higher number of buffer pairs enables a higher degree of
		///   parallelism, which tends to increase the speed of compression on
		///   multi-cpu computers.  On the other hand, a higher number of buffer
		///   pairs also implies a larger memory consumption, more active worker
		///   threads, and a higher cpu utilization for any compression. This
		///   property enables the application to limit its memory consumption and
		///   CPU utilization behavior depending on requirements.
		/// </para>
		///
		/// <para>
		///   For each compression "task" that occurs in parallel, there are 2
		///   buffers allocated: one for input and one for output.  This property
		///   sets a limit for the number of pairs.  The total amount of storage
		///   space allocated for buffering will then be (N*S*2), where N is the
		///   number of buffer pairs, S is the size of each buffer (<see
		///   cref="BufferSize"/>).  By default, DotNetZip allocates 4 buffer
		///   pairs per CPU core, so if your machine has 4 cores, and you retain
		///   the default buffer size of 128k, then the
		///   ParallelDeflateOutputStream will use 4 * 4 * 2 * 128kb of buffer
		///   memory in total, or 4mb, in blocks of 128kb.  If you then set this
		///   property to 8, then the number will be 8 * 2 * 128kb of buffer
		///   memory, or 2mb.
		/// </para>
		///
		/// <para>
		///   CPU utilization will also go up with additional buffers, because a
		///   larger number of buffer pairs allows a larger number of background
		///   threads to compress in parallel. If you find that parallel
		///   compression is consuming too much memory or CPU, you can adjust this
		///   value downward.
		/// </para>
		///
		/// <para>
		///   The default value is 16. Different values may deliver better or
		///   worse results, depending on your priorities and the dynamic
		///   performance characteristics of your storage and compute resources.
		/// </para>
		///
		/// <para>
		///   This property is not the number of buffer pairs to use; it is an
		///   upper limit. An illustration: Suppose you have an application that
		///   uses the default value of this property (which is 16), and it runs
		///   on a machine with 2 CPU cores. In that case, DotNetZip will allocate
		///   4 buffer pairs per CPU core, for a total of 8 pairs.  The upper
		///   limit specified by this property has no effect.
		/// </para>
		///
		/// <para>
		///   The application can set this value at any time
		///   before calling <c>ZipFile.Save()</c>.
		/// </para>
		/// </remarks>
		///
		/// <seealso cref="ParallelDeflateThreshold"/>
		///
		public int ParallelDeflateMaxBufferPairs
		{
			get
			{
				return _maxBufferPairs;
			}
			set
			{
				if (value < 4)
					throw new ArgumentOutOfRangeException("ParallelDeflateMaxBufferPairs",
												"Value must be 4 or greater.");
				_maxBufferPairs = value;
			}
		}
#endif


		/// <summary>Provides a string representation of the instance.</summary>
		/// <returns>a string representation of the instance.</returns>
		public override String ToString()
		{
			return String.Format("ZipFile::{0}", Name);
		}


		/// <summary>
		/// Returns the version number on the DotNetZip assembly.
		/// </summary>
		///
		/// <remarks>
		///   <para>
		///     This property is exposed as a convenience.  Callers could also get the
		///     version value by retrieving GetName().Version on the
		///     System.Reflection.Assembly object pointing to the DotNetZip
		///     assembly. But sometimes it is not clear which assembly is being loaded.
		///     This property makes it clear.
		///   </para>
		///   <para>
		///     This static property is primarily useful for diagnostic purposes.
		///   </para>
		/// </remarks>
		public static System.Version LibraryVersion
		{
			get
			{
				return System.Reflection.Assembly.GetExecutingAssembly().GetName().Version;
			}
		}

		internal void NotifyEntryChanged()
		{
			_contentsChanged = true;
		}


		internal Stream StreamForDiskNumber(uint diskNumber)
		{
			if (diskNumber + 1 == this._diskNumberWithCd ||
				(diskNumber == 0 && this._diskNumberWithCd == 0))
			{
				//return (this.ReadStream as FileStream);
				return this.ReadStream;
			}
			return ZipSegmentedStream.ForReading(this._readName ?? this._name,
												 diskNumber, _diskNumberWithCd);
		}



		// called by ZipEntry in ZipEntry.Extract(), when there is no stream set for the
		// ZipEntry.
		internal void Reset(bool whileSaving)
		{
			if (_JustSaved)
			{
				// read in the just-saved zip archive
				using (ZipFile x = new ZipFile())
				{
					// workitem 10735
					x._readName = x._name = whileSaving
						? (this._readName ?? this._name)
						: this._name;
					x.AlternateEncoding = this.AlternateEncoding;
					x.AlternateEncodingUsage = this.AlternateEncodingUsage;
					ReadIntoInstance(x);
					// copy the contents of the entries.
					// cannot just replace the entries - the app may be holding them
					foreach (ZipEntry e1 in x)
					{
						foreach (ZipEntry e2 in this)
						{
							if (e1.FileName == e2.FileName)
							{
								e2.CopyMetaData(e1);
								break;
							}
						}
					}
				}
				_JustSaved = false;
			}
		}


		#endregion

		#region Constructors

		/// <summary>
		///   Creates a new <c>ZipFile</c> instance, using the specified filename.
		/// </summary>
		///
		/// <remarks>
		/// <para>
		///   Applications can use this constructor to create a new ZipFile for writing,
		///   or to slurp in an existing zip archive for read and update purposes.
		/// </para>
		///
		/// <para>
		///   To create a new zip archive, an application can call this constructor,
		///   passing the name of a file that does not exist.  The name may be a fully
		///   qualified path. Then the application can add directories or files to the
		///   <c>ZipFile</c> via <c>AddDirectory()</c>, <c>AddFile()</c>, <c>AddItem()</c>
		///   and then write the zip archive to the disk by calling <c>Save()</c>. The
		///   zip file is not actually opened and written to the disk until the
		///   application calls <c>ZipFile.Save()</c>.  At that point the new zip file
		///   with the given name is created.
		/// </para>
		///
		/// <para>
		///   If you won't know the name of the <c>Zipfile</c> until the time you call
		///   <c>ZipFile.Save()</c>, or if you plan to save to a stream (which has no
		///   name), then you should use the no-argument constructor.
		/// </para>
		///
		/// <para>
		///   The application can also call this constructor to read an existing zip
		///   archive.  passing the name of a valid zip file that does exist. But, it's
		///   better form to use the static <see cref="ZipFile.Read(String)"/> method,
		///   passing the name of the zip file, because using <c>ZipFile.Read()</c> in
		///   your code communicates very clearly what you are doing.  In either case,
		///   the file is then read into the <c>ZipFile</c> instance.  The app can then
		///   enumerate the entries or can modify the zip file, for example adding
		///   entries, removing entries, changing comments, and so on.
		/// </para>
		///
		/// <para>
		///   One advantage to this parameterized constructor: it allows applications to
		///   use the same code to add items to a zip archive, regardless of whether the
		///   zip file exists.
		/// </para>
		///
		/// <para>
		///   Instances of the <c>ZipFile</c> class are not multi-thread safe.  You may
		///   not party on a single instance with multiple threads.  You may have
		///   multiple threads that each use a distinct <c>ZipFile</c> instance, or you
		///   can synchronize multi-thread access to a single instance.
		/// </para>
		///
		/// <para>
		///   By the way, since DotNetZip is so easy to use, don't you think <see
		///   href="http://cheeso.members.winisp.net/DotNetZipDonate.aspx">you should
		///   donate $5 or $10</see>?
		/// </para>
		///
		/// </remarks>
		///
		/// <exception cref="PickGold.Zip.ZipException">
		/// Thrown if name refers to an existing file that is not a valid zip file.
		/// </exception>
		///
		/// <example>
		/// This example shows how to create a zipfile, and add a few files into it.
		/// <code>
		/// String ZipFileToCreate = "archive1.zip";
		/// String DirectoryToZip  = "c:\\reports";
		/// using (ZipFile zip = new ZipFile())
		/// {
		///   // Store all files found in the top level directory, into the zip archive.
		///   String[] filenames = System.IO.Directory.GetFiles(DirectoryToZip);
		///   zip.AddFiles(filenames, "files");
		///   zip.Save(ZipFileToCreate);
		/// }
		/// </code>
		///
		/// <code lang="VB">
		/// Dim ZipFileToCreate As String = "archive1.zip"
		/// Dim DirectoryToZip As String = "c:\reports"
		/// Using zip As ZipFile = New ZipFile()
		///     Dim filenames As String() = System.IO.Directory.GetFiles(DirectoryToZip)
		///     zip.AddFiles(filenames, "files")
		///     zip.Save(ZipFileToCreate)
		/// End Using
		/// </code>
		/// </example>
		///
		/// <param name="fileName">The filename to use for the new zip archive.</param>
		///
		public ZipFile(string fileName)
		{
			try
			{
				_InitInstance(fileName, null);
			}
			catch (Exception e1)
			{
				throw new ZipException(String.Format("Could not read {0} as a zip file", fileName), e1);
			}
		}


		/// <summary>
		///   Creates a new <c>ZipFile</c> instance, using the specified name for the
		///   filename, and the specified Encoding.
		/// </summary>
		///
		/// <remarks>
		/// <para>
		///   See the documentation on the <see cref="ZipFile(String)">ZipFile
		///   constructor that accepts a single string argument</see> for basic
		///   information on all the <c>ZipFile</c> constructors.
		/// </para>
		///
		/// <para>
		///   The Encoding is used as the default alternate encoding for entries with
		///   filenames or comments that cannot be encoded with the IBM437 code page.
		///   This is equivalent to setting the <see
		///   cref="ProvisionalAlternateEncoding"/> property on the <c>ZipFile</c>
		///   instance after construction.
		/// </para>
		///
		/// <para>
		///   Instances of the <c>ZipFile</c> class are not multi-thread safe.  You may
		///   not party on a single instance with multiple threads.  You may have
		///   multiple threads that each use a distinct <c>ZipFile</c> instance, or you
		///   can synchronize multi-thread access to a single instance.
		/// </para>
		///
		/// </remarks>
		///
		/// <exception cref="PickGold.Zip.ZipException">
		/// Thrown if name refers to an existing file that is not a valid zip file.
		/// </exception>
		///
		/// <param name="fileName">The filename to use for the new zip archive.</param>
		/// <param name="encoding">The Encoding is used as the default alternate
		/// encoding for entries with filenames or comments that cannot be encoded
		/// with the IBM437 code page. </param>
		public ZipFile(string fileName, System.Text.Encoding encoding)
		{
			try
			{
				AlternateEncoding = encoding;
				AlternateEncodingUsage = ZipOption.Always;
				_InitInstance(fileName, null);
			}
			catch (Exception e1)
			{
				throw new ZipException(String.Format("{0} is not a valid zip file", fileName), e1);
			}
		}



		/// <summary>
		///   Create a zip file, without specifying a target filename or stream to save to.
		/// </summary>
		///
		/// <remarks>
		/// <para>
		///   See the documentation on the <see cref="ZipFile(String)">ZipFile
		///   constructor that accepts a single string argument</see> for basic
		///   information on all the <c>ZipFile</c> constructors.
		/// </para>
		///
		/// <para>
		///   After instantiating with this constructor and adding entries to the
		///   archive, the application should call <see cref="ZipFile.Save(String)"/> or
		///   <see cref="ZipFile.Save(System.IO.Stream)"/> to save to a file or a
		///   stream, respectively.  The application can also set the <see cref="Name"/>
		///   property and then call the no-argument <see cref="Save()"/> method.  (This
		///   is the preferred approach for applications that use the library through
		///   COM interop.)  If you call the no-argument <see cref="Save()"/> method
		///   without having set the <c>Name</c> of the <c>ZipFile</c>, either through
		///   the parameterized constructor or through the explicit property , the
		///   Save() will throw, because there is no place to save the file.  </para>
		///
		/// <para>
		///   Instances of the <c>ZipFile</c> class are not multi-thread safe.  You may
		///   have multiple threads that each use a distinct <c>ZipFile</c> instance, or
		///   you can synchronize multi-thread access to a single instance.  </para>
		///
		/// </remarks>
		///
		/// <example>
		/// This example creates a Zip archive called Backup.zip, containing all the files
		/// in the directory DirectoryToZip. Files within subdirectories are not zipped up.
		/// <code>
		/// using (ZipFile zip = new ZipFile())
		/// {
		///   // Store all files found in the top level directory, into the zip archive.
		///   // note: this code does not recurse subdirectories!
		///   String[] filenames = System.IO.Directory.GetFiles(DirectoryToZip);
		///   zip.AddFiles(filenames, "files");
		///   zip.Save("Backup.zip");
		/// }
		/// </code>
		///
		/// <code lang="VB">
		/// Using zip As New ZipFile
		///     ' Store all files found in the top level directory, into the zip archive.
		///     ' note: this code does not recurse subdirectories!
		///     Dim filenames As String() = System.IO.Directory.GetFiles(DirectoryToZip)
		///     zip.AddFiles(filenames, "files")
		///     zip.Save("Backup.zip")
		/// End Using
		/// </code>
		/// </example>
		public ZipFile()
		{
			_InitInstance(null, null);
		}


		/// <summary>
		///   Create a zip file, specifying a text Encoding, but without specifying a
		///   target filename or stream to save to.
		/// </summary>
		///
		/// <remarks>
		/// <para>
		///   See the documentation on the <see cref="ZipFile(String)">ZipFile
		///   constructor that accepts a single string argument</see> for basic
		///   information on all the <c>ZipFile</c> constructors.
		/// </para>
		///
		/// </remarks>
		///
		/// <param name="encoding">
		/// The Encoding is used as the default alternate encoding for entries with
		/// filenames or comments that cannot be encoded with the IBM437 code page.
		/// </param>
		public ZipFile(System.Text.Encoding encoding)
		{
			AlternateEncoding = encoding;
			AlternateEncodingUsage = ZipOption.Always;
			_InitInstance(null, null);
		}


		/// <summary>
		///   Creates a new <c>ZipFile</c> instance, using the specified name for the
		///   filename, and the specified status message writer.
		/// </summary>
		///
		/// <remarks>
		/// <para>
		///   See the documentation on the <see cref="ZipFile(String)">ZipFile
		///   constructor that accepts a single string argument</see> for basic
		///   information on all the <c>ZipFile</c> constructors.
		/// </para>
		///
		/// <para>
		///   This version of the constructor allows the caller to pass in a TextWriter,
		///   to which verbose messages will be written during extraction or creation of
		///   the zip archive.  A console application may wish to pass
		///   System.Console.Out to get messages on the Console. A graphical or headless
		///   application may wish to capture the messages in a different
		///   <c>TextWriter</c>, for example, a <c>StringWriter</c>, and then display
		///   the messages in a TextBox, or generate an audit log of ZipFile operations.
		/// </para>
		///
		/// <para>
		///   To encrypt the data for the files added to the <c>ZipFile</c> instance,
		///   set the Password property after creating the <c>ZipFile</c> instance.
		/// </para>
		///
		/// <para>
		///   Instances of the <c>ZipFile</c> class are not multi-thread safe.  You may
		///   not party on a single instance with multiple threads.  You may have
		///   multiple threads that each use a distinct <c>ZipFile</c> instance, or you
		///   can synchronize multi-thread access to a single instance.
		/// </para>
		///
		/// </remarks>
		///
		/// <exception cref="PickGold.Zip.ZipException">
		/// Thrown if name refers to an existing file that is not a valid zip file.
		/// </exception>
		///
		/// <example>
		/// <code>
		/// using (ZipFile zip = new ZipFile("Backup.zip", Console.Out))
		/// {
		///   // Store all files found in the top level directory, into the zip archive.
		///   // note: this code does not recurse subdirectories!
		///   // Status messages will be written to Console.Out
		///   String[] filenames = System.IO.Directory.GetFiles(DirectoryToZip);
		///   zip.AddFiles(filenames);
		///   zip.Save();
		/// }
		/// </code>
		///
		/// <code lang="VB">
		/// Using zip As New ZipFile("Backup.zip", Console.Out)
		///     ' Store all files found in the top level directory, into the zip archive.
		///     ' note: this code does not recurse subdirectories!
		///     ' Status messages will be written to Console.Out
		///     Dim filenames As String() = System.IO.Directory.GetFiles(DirectoryToZip)
		///     zip.AddFiles(filenames)
		///     zip.Save()
		/// End Using
		/// </code>
		/// </example>
		///
		/// <param name="fileName">The filename to use for the new zip archive.</param>
		/// <param name="statusMessageWriter">A TextWriter to use for writing
		/// verbose status messages.</param>
		public ZipFile(string fileName, TextWriter statusMessageWriter)
		{
			try
			{
				_InitInstance(fileName, statusMessageWriter);
			}
			catch (Exception e1)
			{
				throw new ZipException(String.Format("{0} is not a valid zip file", fileName), e1);
			}
		}


		/// <summary>
		///   Creates a new <c>ZipFile</c> instance, using the specified name for the
		///   filename, the specified status message writer, and the specified Encoding.
		/// </summary>
		///
		/// <remarks>
		/// <para>
		///   This constructor works like the <see cref="ZipFile(String)">ZipFile
		///   constructor that accepts a single string argument.</see> See that
		///   reference for detail on what this constructor does.
		/// </para>
		///
		/// <para>
		///   This version of the constructor allows the caller to pass in a
		///   <c>TextWriter</c>, and an Encoding.  The <c>TextWriter</c> will collect
		///   verbose messages that are generated by the library during extraction or
		///   creation of the zip archive.  A console application may wish to pass
		///   <c>System.Console.Out</c> to get messages on the Console. A graphical or
		///   headless application may wish to capture the messages in a different
		///   <c>TextWriter</c>, for example, a <c>StringWriter</c>, and then display
		///   the messages in a <c>TextBox</c>, or generate an audit log of
		///   <c>ZipFile</c> operations.
		/// </para>
		///
		/// <para>
		///   The <c>Encoding</c> is used as the default alternate encoding for entries
		///   with filenames or comments that cannot be encoded with the IBM437 code
		///   page.  This is a equivalent to setting the <see
		///   cref="ProvisionalAlternateEncoding"/> property on the <c>ZipFile</c>
		///   instance after construction.
		/// </para>
		///
		/// <para>
		///   To encrypt the data for the files added to the <c>ZipFile</c> instance,
		///   set the <c>Password</c> property after creating the <c>ZipFile</c>
		///   instance.
		/// </para>
		///
		/// <para>
		///   Instances of the <c>ZipFile</c> class are not multi-thread safe.  You may
		///   not party on a single instance with multiple threads.  You may have
		///   multiple threads that each use a distinct <c>ZipFile</c> instance, or you
		///   can synchronize multi-thread access to a single instance.
		/// </para>
		///
		/// </remarks>
		///
		/// <exception cref="PickGold.Zip.ZipException">
		/// Thrown if <c>fileName</c> refers to an existing file that is not a valid zip file.
		/// </exception>
		///
		/// <param name="fileName">The filename to use for the new zip archive.</param>
		/// <param name="statusMessageWriter">A TextWriter to use for writing verbose
		/// status messages.</param>
		/// <param name="encoding">
		/// The Encoding is used as the default alternate encoding for entries with
		/// filenames or comments that cannot be encoded with the IBM437 code page.
		/// </param>
		public ZipFile(string fileName, TextWriter statusMessageWriter,
					   System.Text.Encoding encoding)
		{
			try
			{
				AlternateEncoding = encoding;
				AlternateEncodingUsage = ZipOption.Always;
				_InitInstance(fileName, statusMessageWriter);
			}
			catch (Exception e1)
			{
				throw new ZipException(String.Format("{0} is not a valid zip file", fileName), e1);
			}
		}




		/// <summary>
		///   Initialize a <c>ZipFile</c> instance by reading in a zip file.
		/// </summary>
		///
		/// <remarks>
		///
		/// <para>
		///   This method is primarily useful from COM Automation environments, when
		///   reading or extracting zip files. In COM, it is not possible to invoke
		///   parameterized constructors for a class. A COM Automation application can
		///   update a zip file by using the <see cref="ZipFile()">default (no argument)
		///   constructor</see>, then calling <c>Initialize()</c> to read the contents
		///   of an on-disk zip archive into the <c>ZipFile</c> instance.
		/// </para>
		///
		/// <para>
		///   .NET applications are encouraged to use the <c>ZipFile.Read()</c> methods
		///   for better clarity.
		/// </para>
		///
		/// </remarks>
		/// <param name="fileName">the name of the existing zip file to read in.</param>
		public void Initialize(string fileName)
		{
			try
			{
				_InitInstance(fileName, null);
			}
			catch (Exception e1)
			{
				throw new ZipException(String.Format("{0} is not a valid zip file", fileName), e1);
			}
		}



		private void _initEntriesDictionary()
		{
			// workitem 9868
			StringComparer sc = (CaseSensitiveRetrieval) ? StringComparer.Ordinal : StringComparer.OrdinalIgnoreCase;
			_entries = (_entries == null)
				? new Dictionary<String, ZipEntry>(sc)
				: new Dictionary<String, ZipEntry>(_entries, sc);
		}


		private void _InitInstance(string zipFileName, TextWriter statusMessageWriter)
		{
			// create a new zipfile
			_name = zipFileName;
			_StatusMessageTextWriter = statusMessageWriter;
			_contentsChanged = true;
			AddDirectoryWillTraverseReparsePoints = true;  // workitem 8617
			CompressionLevel = PickGold.Zlib.CompressionLevel.Default;
#if !NETCF
			ParallelDeflateThreshold = 512 * 1024;
#endif
			// workitem 7685, 9868
			_initEntriesDictionary();

			if (File.Exists(_name))
			{
				if (FullScan)
					ReadIntoInstance_Orig(this);
				else
					ReadIntoInstance(this);
				this._fileAlreadyExists = true;
			}

			return;
		}
		#endregion



		#region Indexers and Collections

		private List<ZipEntry> ZipEntriesAsList
		{
			get
			{
				if (_zipEntriesAsList == null)
					_zipEntriesAsList = new List<ZipEntry>(_entries.Values);
				return _zipEntriesAsList;
			}
		}

		/// <summary>
		///   This is an integer indexer into the Zip archive.
		/// </summary>
		///
		/// <remarks>
		/// <para>
		///   This property is read-only.
		/// </para>
		///
		/// <para>
		///   Internally, the <c>ZipEntry</c> instances that belong to the
		///   <c>ZipFile</c> are stored in a Dictionary.  When you use this
		///   indexer the first time, it creates a read-only
		///   <c>List&lt;ZipEntry&gt;</c> from the Dictionary.Values Collection.
		///   If at any time you modify the set of entries in the <c>ZipFile</c>,
		///   either by adding an entry, removing an entry, or renaming an
		///   entry, a new List will be created, and the numeric indexes for the
		///   remaining entries may be different.
		/// </para>
		///
		/// <para>
		///   This means you cannot rename any ZipEntry from
		///   inside an enumeration of the zip file.
		/// </para>
		///
		/// <param name="ix">
		///   The index value.
		/// </param>
		///
		/// </remarks>
		///
		/// <returns>
		///   The <c>ZipEntry</c> within the Zip archive at the specified index. If the
		///   entry does not exist in the archive, this indexer throws.
		/// </returns>
		///
		public ZipEntry this[int ix]
		{
			// workitem 6402
			get
			{
				return ZipEntriesAsList[ix];
			}
		}


		/// <summary>
		///   This is a name-based indexer into the Zip archive.
		/// </summary>
		///
		/// <remarks>
		/// <para>
		///   This property is read-only.
		/// </para>
		///
		/// <para>
		///   The <see cref="CaseSensitiveRetrieval"/> property on the <c>ZipFile</c>
		///   determines whether retrieval via this indexer is done via case-sensitive
		///   comparisons. By default, retrieval is not case sensitive.  This makes
		///   sense on Windows, in which filesystems are not case sensitive.
		/// </para>
		///
		/// <para>
		///   Regardless of case-sensitivity, it is not always the case that
		///   <c>this[value].FileName == value</c>. In other words, the <c>FileName</c>
		///   property of the <c>ZipEntry</c> retrieved with this indexer, may or may
		///   not be equal to the index value.
		/// </para>
		///
		/// <para>
		///   This is because DotNetZip performs a normalization of filenames passed to
		///   this indexer, before attempting to retrieve the item.  That normalization
		///   includes: removal of a volume letter and colon, swapping backward slashes
		///   for forward slashes.  So, <c>zip["dir1\\entry1.txt"].FileName ==
		///   "dir1/entry.txt"</c>.
		/// </para>
		///
		/// <para>
		///   Directory entries in the zip file may be retrieved via this indexer only
		///   with names that have a trailing slash. DotNetZip automatically appends a
		///   trailing slash to the names of any directory entries added to a zip.
		/// </para>
		///
		/// </remarks>
		///
		/// <example>
		/// This example extracts only the entries in a zip file that are .txt files.
		/// <code>
		/// using (ZipFile zip = ZipFile.Read("PackedDocuments.zip"))
		/// {
		///   foreach (string s1 in zip.EntryFilenames)
		///   {
		///     if (s1.EndsWith(".txt"))
		///       zip[s1].Extract("textfiles");
		///   }
		/// }
		/// </code>
		/// <code lang="VB">
		///   Using zip As ZipFile = ZipFile.Read("PackedDocuments.zip")
		///       Dim s1 As String
		///       For Each s1 In zip.EntryFilenames
		///           If s1.EndsWith(".txt") Then
		///               zip(s1).Extract("textfiles")
		///           End If
		///       Next
		///   End Using
		/// </code>
		/// </example>
		/// <seealso cref="PickGold.Zip.ZipFile.RemoveEntry(string)"/>
		///
		/// <exception cref="System.ArgumentException">
		///   Thrown if the caller attempts to assign a non-null value to the indexer.
		/// </exception>
		///
		/// <param name="fileName">
		///   The name of the file, including any directory path, to retrieve from the
		///   zip.  The filename match is not case-sensitive by default; you can use the
		///   <see cref="CaseSensitiveRetrieval"/> property to change this behavior. The
		///   pathname can use forward-slashes or backward slashes.
		/// </param>
		///
		/// <returns>
		///   The <c>ZipEntry</c> within the Zip archive, given by the specified
		///   filename. If the named entry does not exist in the archive, this indexer
		///   returns <c>null</c> (<c>Nothing</c> in VB).
		/// </returns>
		///
		public ZipEntry this[String fileName]
		{
			get
			{
				var key = SharedUtilities.NormalizePathForUseInZipFile(fileName);
				if (_entries.ContainsKey(key))
					return _entries[key];
				// workitem 11056
				key = key.Replace("/", "\\");
				if (_entries.ContainsKey(key))
					return _entries[key];
				return null;

#if MESSY
                foreach (ZipEntry e in _entries.Values)
                {
                    if (this.CaseSensitiveRetrieval)
                    {
                        // check for the file match with a case-sensitive comparison.
                        if (e.FileName == fileName) return e;
                        // also check for equivalence
                        if (fileName.Replace("\\", "/") == e.FileName) return e;
                        if (e.FileName.Replace("\\", "/") == fileName) return e;

                        // check for a difference only in trailing slash
                        if (e.FileName.EndsWith("/"))
                        {
                            var fileNameNoSlash = e.FileName.Trim("/".ToCharArray());
                            if (fileNameNoSlash == fileName) return e;
                            // also check for equivalence
                            if (fileName.Replace("\\", "/") == fileNameNoSlash) return e;
                            if (fileNameNoSlash.Replace("\\", "/") == fileName) return e;
                        }

                    }
                    else
                    {
                        // check for the file match in a case-insensitive manner.
                        if (String.Compare(e.FileName, fileName, StringComparison.CurrentCultureIgnoreCase) == 0) return e;
                        // also check for equivalence
                        if (String.Compare(fileName.Replace("\\", "/"), e.FileName, StringComparison.CurrentCultureIgnoreCase) == 0) return e;
                        if (String.Compare(e.FileName.Replace("\\", "/"), fileName, StringComparison.CurrentCultureIgnoreCase) == 0) return e;

                        // check for a difference only in trailing slash
                        if (e.FileName.EndsWith("/"))
                        {
                            var fileNameNoSlash = e.FileName.Trim("/".ToCharArray());

                            if (String.Compare(fileNameNoSlash, fileName, StringComparison.CurrentCultureIgnoreCase) == 0) return e;
                            // also check for equivalence
                            if (String.Compare(fileName.Replace("\\", "/"), fileNameNoSlash, StringComparison.CurrentCultureIgnoreCase) == 0) return e;
                            if (String.Compare(fileNameNoSlash.Replace("\\", "/"), fileName, StringComparison.CurrentCultureIgnoreCase) == 0) return e;

                        }

                    }

                }
                return null;

#endif
			}
		}


		/// <summary>
		///   The list of filenames for the entries contained within the zip archive.
		/// </summary>
		///
		/// <remarks>
		///   According to the ZIP specification, the names of the entries use forward
		///   slashes in pathnames.  If you are scanning through the list, you may have
		///   to swap forward slashes for backslashes.
		/// </remarks>
		///
		/// <seealso cref="PickGold.Zip.ZipFile.this[string]"/>
		///
		/// <example>
		///   This example shows one way to test if a filename is already contained
		///   within a zip archive.
		/// <code>
		/// String zipFileToRead= "PackedDocuments.zip";
		/// string candidate = "DatedMaterial.xps";
		/// using (ZipFile zip = new ZipFile(zipFileToRead))
		/// {
		///   if (zip.EntryFilenames.Contains(candidate))
		///     Console.WriteLine("The file '{0}' exists in the zip archive '{1}'",
		///                       candidate,
		///                       zipFileName);
		///   else
		///     Console.WriteLine("The file, '{0}', does not exist in the zip archive '{1}'",
		///                       candidate,
		///                       zipFileName);
		///   Console.WriteLine();
		/// }
		/// </code>
		/// <code lang="VB">
		///   Dim zipFileToRead As String = "PackedDocuments.zip"
		///   Dim candidate As String = "DatedMaterial.xps"
		///   Using zip As ZipFile.Read(ZipFileToRead)
		///       If zip.EntryFilenames.Contains(candidate) Then
		///           Console.WriteLine("The file '{0}' exists in the zip archive '{1}'", _
		///                       candidate, _
		///                       zipFileName)
		///       Else
		///         Console.WriteLine("The file, '{0}', does not exist in the zip archive '{1}'", _
		///                       candidate, _
		///                       zipFileName)
		///       End If
		///       Console.WriteLine
		///   End Using
		/// </code>
		/// </example>
		///
		/// <returns>
		///   The list of strings for the filenames contained within the Zip archive.
		/// </returns>
		///
		public System.Collections.Generic.ICollection<String> EntryFileNames
		{
			get
			{
				return _entries.Keys;
			}
		}


		/// <summary>
		///   Returns the readonly collection of entries in the Zip archive.
		/// </summary>
		///
		/// <remarks>
		///
		/// <para>
		///   If there are no entries in the current <c>ZipFile</c>, the value returned is a
		///   non-null zero-element collection.  If there are entries in the zip file,
		///   the elements are returned in no particular order.
		/// </para>
		/// <para>
		///   This is the implied enumerator on the <c>ZipFile</c> class.  If you use a
		///   <c>ZipFile</c> instance in a context that expects an enumerator, you will
		///   get this collection.
		/// </para>
		/// </remarks>
		/// <seealso cref="EntriesSorted"/>
		public System.Collections.Generic.ICollection<ZipEntry> Entries
		{
			get
			{
				return _entries.Values;
			}
		}


		/// <summary>
		///   Returns a readonly collection of entries in the Zip archive, sorted by FileName.
		/// </summary>
		///
		/// <remarks>
		///   If there are no entries in the current <c>ZipFile</c>, the value returned
		///   is a non-null zero-element collection.  If there are entries in the zip
		///   file, the elements are returned sorted by the name of the entry.
		/// </remarks>
		///
		/// <example>
		///
		///   This example fills a Windows Forms ListView with the entries in a zip file.
		///
		/// <code lang="C#">
		/// using (ZipFile zip = ZipFile.Read(zipFile))
		/// {
		///     foreach (ZipEntry entry in zip.EntriesSorted)
		///     {
		///         ListViewItem item = new ListViewItem(n.ToString());
		///         n++;
		///         string[] subitems = new string[] {
		///             entry.FileName.Replace("/","\\"),
		///             entry.LastModified.ToString("yyyy-MM-dd HH:mm:ss"),
		///             entry.UncompressedSize.ToString(),
		///             String.Format("{0,5:F0}%", entry.CompressionRatio),
		///             entry.CompressedSize.ToString(),
		///             (entry.UsesEncryption) ? "Y" : "N",
		///             String.Format("{0:X8}", entry.Crc)};
		///
		///         foreach (String s in subitems)
		///         {
		///             ListViewItem.ListViewSubItem subitem = new ListViewItem.ListViewSubItem();
		///             subitem.Text = s;
		///             item.SubItems.Add(subitem);
		///         }
		///
		///         this.listView1.Items.Add(item);
		///     }
		/// }
		/// </code>
		/// </example>
		///
		/// <seealso cref="Entries"/>
		public System.Collections.Generic.ICollection<ZipEntry> EntriesSorted
		{
			get
			{
				var coll = new System.Collections.Generic.List<ZipEntry>();
				foreach (var e in this.Entries)
				{
					coll.Add(e);
				}
				StringComparison sc = (CaseSensitiveRetrieval) ? StringComparison.Ordinal : StringComparison.OrdinalIgnoreCase;

				coll.Sort((x, y) => { return String.Compare(x.FileName, y.FileName, sc); });
				return coll.AsReadOnly();
			}
		}


		/// <summary>
		/// Returns the number of entries in the Zip archive.
		/// </summary>
		public int Count
		{
			get
			{
				return _entries.Count;
			}
		}



		/// <summary>
		///   Removes the given <c>ZipEntry</c> from the zip archive.
		/// </summary>
		///
		/// <remarks>
		/// <para>
		///   After calling <c>RemoveEntry</c>, the application must call <c>Save</c> to
		///   make the changes permanent.
		/// </para>
		/// </remarks>
		///
		/// <exception cref="System.ArgumentException">
		///   Thrown if the specified <c>ZipEntry</c> does not exist in the <c>ZipFile</c>.
		/// </exception>
		///
		/// <example>
		///   In this example, all entries in the zip archive dating from before
		///   December 31st, 2007, are removed from the archive.  This is actually much
		///   easier if you use the RemoveSelectedEntries method.  But I needed an
		///   example for RemoveEntry, so here it is.
		/// <code>
		/// String ZipFileToRead = "ArchiveToModify.zip";
		/// System.DateTime Threshold = new System.DateTime(2007,12,31);
		/// using (ZipFile zip = ZipFile.Read(ZipFileToRead))
		/// {
		///   var EntriesToRemove = new System.Collections.Generic.List&lt;ZipEntry&gt;();
		///   foreach (ZipEntry e in zip)
		///   {
		///     if (e.LastModified &lt; Threshold)
		///     {
		///       // We cannot remove the entry from the list, within the context of
		///       // an enumeration of said list.
		///       // So we add the doomed entry to a list to be removed later.
		///       EntriesToRemove.Add(e);
		///     }
		///   }
		///
		///   // actually remove the doomed entries.
		///   foreach (ZipEntry zombie in EntriesToRemove)
		///     zip.RemoveEntry(zombie);
		///
		///   zip.Comment= String.Format("This zip archive was updated at {0}.",
		///                              System.DateTime.Now.ToString("G"));
		///
		///   // save with a different name
		///   zip.Save("Archive-Updated.zip");
		/// }
		/// </code>
		///
		/// <code lang="VB">
		///   Dim ZipFileToRead As String = "ArchiveToModify.zip"
		///   Dim Threshold As New DateTime(2007, 12, 31)
		///   Using zip As ZipFile = ZipFile.Read(ZipFileToRead)
		///       Dim EntriesToRemove As New System.Collections.Generic.List(Of ZipEntry)
		///       Dim e As ZipEntry
		///       For Each e In zip
		///           If (e.LastModified &lt; Threshold) Then
		///               ' We cannot remove the entry from the list, within the context of
		///               ' an enumeration of said list.
		///               ' So we add the doomed entry to a list to be removed later.
		///               EntriesToRemove.Add(e)
		///           End If
		///       Next
		///
		///       ' actually remove the doomed entries.
		///       Dim zombie As ZipEntry
		///       For Each zombie In EntriesToRemove
		///           zip.RemoveEntry(zombie)
		///       Next
		///       zip.Comment = String.Format("This zip archive was updated at {0}.", DateTime.Now.ToString("G"))
		///       'save as a different name
		///       zip.Save("Archive-Updated.zip")
		///   End Using
		/// </code>
		/// </example>
		///
		/// <param name="entry">
		/// The <c>ZipEntry</c> to remove from the zip.
		/// </param>
		///
		/// <seealso cref="PickGold.Zip.ZipFile.RemoveSelectedEntries(string)"/>
		///
		public void RemoveEntry(ZipEntry entry)
		{
			//if (!_entries.Values.Contains(entry))
			//    throw new ArgumentException("The entry you specified does not exist in the zip archive.");
			if (entry == null)
				throw new ArgumentNullException("entry");

			_entries.Remove(SharedUtilities.NormalizePathForUseInZipFile(entry.FileName));
			_zipEntriesAsList = null;

#if NOTNEEDED
            if (_direntries != null)
            {
                bool FoundAndRemovedDirEntry = false;
                foreach (ZipDirEntry de1 in _direntries)
                {
                    if (entry.FileName == de1.FileName)
                    {
                        _direntries.Remove(de1);
                        FoundAndRemovedDirEntry = true;
                        break;
                    }
                }

                if (!FoundAndRemovedDirEntry)
                    throw new BadStateException("The entry to be removed was not found in the directory.");
            }
#endif
			_contentsChanged = true;
		}




		/// <summary>
		/// Removes the <c>ZipEntry</c> with the given filename from the zip archive.
		/// </summary>
		///
		/// <remarks>
		/// <para>
		///   After calling <c>RemoveEntry</c>, the application must call <c>Save</c> to
		///   make the changes permanent.
		/// </para>
		///
		/// </remarks>
		///
		/// <exception cref="System.InvalidOperationException">
		///   Thrown if the <c>ZipFile</c> is not updatable.
		/// </exception>
		///
		/// <exception cref="System.ArgumentException">
		///   Thrown if a <c>ZipEntry</c> with the specified filename does not exist in
		///   the <c>ZipFile</c>.
		/// </exception>
		///
		/// <example>
		///
		///   This example shows one way to remove an entry with a given filename from
		///   an existing zip archive.
		///
		/// <code>
		/// String zipFileToRead= "PackedDocuments.zip";
		/// string candidate = "DatedMaterial.xps";
		/// using (ZipFile zip = ZipFile.Read(zipFileToRead))
		/// {
		///   if (zip.EntryFilenames.Contains(candidate))
		///   {
		///     zip.RemoveEntry(candidate);
		///     zip.Comment= String.Format("The file '{0}' has been removed from this archive.",
		///                                Candidate);
		///     zip.Save();
		///   }
		/// }
		/// </code>
		/// <code lang="VB">
		///   Dim zipFileToRead As String = "PackedDocuments.zip"
		///   Dim candidate As String = "DatedMaterial.xps"
		///   Using zip As ZipFile = ZipFile.Read(zipFileToRead)
		///       If zip.EntryFilenames.Contains(candidate) Then
		///           zip.RemoveEntry(candidate)
		///           zip.Comment = String.Format("The file '{0}' has been removed from this archive.", Candidate)
		///           zip.Save
		///       End If
		///   End Using
		/// </code>
		/// </example>
		///
		/// <param name="fileName">
		/// The name of the file, including any directory path, to remove from the zip.
		/// The filename match is not case-sensitive by default; you can use the
		/// <c>CaseSensitiveRetrieval</c> property to change this behavior. The
		/// pathname can use forward-slashes or backward slashes.
		/// </param>
		///
		public void RemoveEntry(String fileName)
		{
			string modifiedName = ZipEntry.NameInArchive(fileName, null);
			ZipEntry e = this[modifiedName];
			if (e == null)
				throw new ArgumentException("The entry you specified was not found in the zip archive.");

			RemoveEntry(e);
		}


		#endregion

		#region Destructors and Disposers

		//         /// <summary>
		//         /// This is the class Destructor, which gets called implicitly when the instance
		//         /// is destroyed.  Because the <c>ZipFile</c> type implements IDisposable, this
		//         /// method calls Dispose(false).
		//         /// </summary>
		//         ~ZipFile()
		//         {
		//             // call Dispose with false.  Since we're in the
		//             // destructor call, the managed resources will be
		//             // disposed of anyways.
		//             Dispose(false);
		//         }

		/// <summary>
		///   Closes the read and write streams associated
		///   to the <c>ZipFile</c>, if necessary.
		/// </summary>
		///
		/// <remarks>
		///   The Dispose() method is generally employed implicitly, via a <c>using(..) {..}</c>
		///   statement. (<c>Using...End Using</c> in VB) If you do not employ a using
		///   statement, insure that your application calls Dispose() explicitly.  For
		///   example, in a Powershell application, or an application that uses the COM
		///   interop interface, you must call Dispose() explicitly.
		/// </remarks>
		///
		/// <example>
		/// This example extracts an entry selected by name, from the Zip file to the
		/// Console.
		/// <code>
		/// using (ZipFile zip = ZipFile.Read(zipfile))
		/// {
		///   foreach (ZipEntry e in zip)
		///   {
		///     if (WantThisEntry(e.FileName))
		///       zip.Extract(e.FileName, Console.OpenStandardOutput());
		///   }
		/// } // Dispose() is called implicitly here.
		/// </code>
		///
		/// <code lang="VB">
		/// Using zip As ZipFile = ZipFile.Read(zipfile)
		///     Dim e As ZipEntry
		///     For Each e In zip
		///       If WantThisEntry(e.FileName) Then
		///           zip.Extract(e.FileName, Console.OpenStandardOutput())
		///       End If
		///     Next
		/// End Using ' Dispose is implicity called here
		/// </code>
		/// </example>
		public void Dispose()
		{
			// dispose of the managed and unmanaged resources
			Dispose(true);

			// tell the GC that the Finalize process no longer needs
			// to be run for this object.
			GC.SuppressFinalize(this);
		}

		/// <summary>
		///   Disposes any managed resources, if the flag is set, then marks the
		///   instance disposed.  This method is typically not called explicitly from
		///   application code.
		/// </summary>
		///
		/// <remarks>
		///   Applications should call <see cref="Dispose()">the no-arg Dispose method</see>.
		/// </remarks>
		///
		/// <param name="disposeManagedResources">
		///   indicates whether the method should dispose streams or not.
		/// </param>
		protected virtual void Dispose(bool disposeManagedResources)
		{
			if (!this._disposed)
			{
				if (disposeManagedResources)
				{
					// dispose managed resources
					if (_ReadStreamIsOurs)
					{
						if (_readstream != null)
						{
							// workitem 7704
#if NETCF
                            _readstream.Close();
#else
							_readstream.Dispose();
#endif
							_readstream = null;
						}
					}
					// only dispose the writestream if there is a backing file
					if ((_temporaryFileName != null) && (_name != null))
						if (_writestream != null)
						{
							// workitem 7704
#if NETCF
                            _writestream.Close();
#else
							_writestream.Dispose();
#endif
							_writestream = null;
						}

#if !NETCF
					// workitem 10030
					if (this.ParallelDeflater != null)
					{
						this.ParallelDeflater.Dispose();
						this.ParallelDeflater = null;
					}
#endif
				}
				this._disposed = true;
			}
		}
		#endregion


		#region private properties

		internal Stream ReadStream
		{
			get
			{
				if (_readstream == null)
				{
					if (_readName != null || _name != null)
					{
						_readstream = File.Open(_readName ?? _name,
												FileMode.Open,
												FileAccess.Read,
												FileShare.Read | FileShare.Write);
						_ReadStreamIsOurs = true;
					}
				}
				return _readstream;
			}
		}



		private Stream WriteStream
		{
			// workitem 9763
			get
			{
				if (_writestream != null) return _writestream;
				if (_name == null) return _writestream;

				if (_maxOutputSegmentSize != 0)
				{
					_writestream = ZipSegmentedStream.ForWriting(this._name, _maxOutputSegmentSize);
					return _writestream;
				}

				SharedUtilities.CreateAndOpenUniqueTempFile(TempFileFolder ?? Path.GetDirectoryName(_name),
															out _writestream,
															out _temporaryFileName);
				return _writestream;
			}
			set
			{
				if (value != null)
					throw new ZipException("Cannot set the stream to a non-null value.");
				_writestream = null;
			}
		}
		#endregion

		#region private fields
		private TextWriter _StatusMessageTextWriter;
		private bool _CaseSensitiveRetrieval;
		private Stream _readstream;
		private Stream _writestream;
		private UInt16 _versionMadeBy;
		private UInt16 _versionNeededToExtract;
		private UInt32 _diskNumberWithCd;
		private Int32 _maxOutputSegmentSize;
		private UInt32 _numberOfSegmentsForMostRecentSave;
		private ZipErrorAction _zipErrorAction;
		private bool _disposed;
		//private System.Collections.Generic.List<ZipEntry> _entries;
		private System.Collections.Generic.Dictionary<String, ZipEntry> _entries;
		private List<ZipEntry> _zipEntriesAsList;
		private string _name;
		private string _readName;
		private string _Comment;
		internal string _Password;
		private bool _emitNtfsTimes = true;
		private bool _emitUnixTimes;
		private PickGold.Zlib.CompressionStrategy _Strategy = PickGold.Zlib.CompressionStrategy.Default;
		private PickGold.Zip.CompressionMethod _compressionMethod = PickGold.Zip.CompressionMethod.Deflate;
		private bool _fileAlreadyExists;
		private string _temporaryFileName;
		private bool _contentsChanged;
		private bool _hasBeenSaved;
		private String _TempFileFolder;
		private bool _ReadStreamIsOurs = true;
		private object LOCK = new object();
		private bool _saveOperationCanceled;
		private bool _extractOperationCanceled;
		private bool _addOperationCanceled;
		private EncryptionAlgorithm _Encryption;
		private bool _JustSaved;
		private long _locEndOfCDS = -1;
		private uint _OffsetOfCentralDirectory;
		private Int64 _OffsetOfCentralDirectory64;
		private Nullable<bool> _OutputUsesZip64;
		internal bool _inExtractAll;
		private System.Text.Encoding _alternateEncoding = System.Text.Encoding.GetEncoding("IBM437"); // UTF-8
		private ZipOption _alternateEncodingUsage = ZipOption.Never;
		private static System.Text.Encoding _defaultEncoding = System.Text.Encoding.GetEncoding("IBM437");

		private int _BufferSize = BufferSizeDefault;

#if !NETCF
		internal PickGold.Zlib.ParallelDeflateOutputStream ParallelDeflater;
		private long _ParallelDeflateThreshold;
		private int _maxBufferPairs = 16;
#endif

		internal Zip64Option _zip64 = Zip64Option.Default;
#pragma warning disable 649
		private bool _SavingSfx;
#pragma warning restore 649

		/// <summary>
		///   Default size of the buffer used for IO.
		/// </summary>
		public static readonly int BufferSizeDefault = 32768;

		#endregion
	}

	/// <summary>
	///   Options for using ZIP64 extensions when saving zip archives.
	/// </summary>
	///
	/// <remarks>
	///
	/// <para>
	///   Designed many years ago, the <see
	///   href="http://www.pkware.com/documents/casestudies/APPNOTE.TXT">original zip
	///   specification from PKWARE</see> allowed for 32-bit quantities for the
	///   compressed and uncompressed sizes of zip entries, as well as a 32-bit quantity
	///   for specifying the length of the zip archive itself, and a maximum of 65535
	///   entries.  These limits are now regularly exceeded in many backup and archival
	///   scenarios.  Recently, PKWare added extensions to the original zip spec, called
	///   "ZIP64 extensions", to raise those limitations.  This property governs whether
	///   DotNetZip will use those extensions when writing zip archives. The use of
	///   these extensions is optional and explicit in DotNetZip because, despite the
	///   status of ZIP64 as a bona fide standard, many other zip tools and libraries do
	///   not support ZIP64, and therefore a zip file with ZIP64 extensions may be
	///   unreadable by some of those other tools.
	/// </para>
	///
	/// <para>
	///   Set this property to <see cref="Zip64Option.Always"/> to always use ZIP64
	///   extensions when saving, regardless of whether your zip archive needs it.
	///   Suppose you add 5 files, each under 100k, to a ZipFile. If you specify Always
	///   for this flag, you will get a ZIP64 archive, though the archive does not need
	///   to use ZIP64 because none of the original zip limits had been exceeded.
	/// </para>
	///
	/// <para>
	///   Set this property to <see cref="Zip64Option.Never"/> to tell the DotNetZip
	///   library to never use ZIP64 extensions.  This is useful for maximum
	///   compatibility and interoperability, at the expense of the capability of
	///   handling large files or large archives.  NB: Windows Explorer in Windows XP
	///   and Windows Vista cannot currently extract files from a zip64 archive, so if
	///   you want to guarantee that a zip archive produced by this library will work in
	///   Windows Explorer, use <c>Never</c>. If you set this property to <see
	///   cref="Zip64Option.Never"/>, and your application creates a zip that would
	///   exceed one of the Zip limits, the library will throw an exception while saving
	///   the zip file.
	/// </para>
	///
	/// <para>
	///   Set this property to <see cref="Zip64Option.AsNecessary"/> to tell the
	///   DotNetZip library to use the ZIP64 extensions when required by the
	///   entry. After the file is compressed, the original and compressed sizes are
	///   checked, and if they exceed the limits described above, then zip64 can be
	///   used. That is the general idea, but there is an additional wrinkle when saving
	///   to a non-seekable device, like the ASP.NET <c>Response.OutputStream</c>, or
	///   <c>Console.Out</c>.  When using non-seekable streams for output, the entry
	///   header - which indicates whether zip64 is in use - is emitted before it is
	///   known if zip64 is necessary.  It is only after all entries have been saved
	///   that it can be known if ZIP64 will be required.  On seekable output streams,
	///   after saving all entries, the library can seek backward and re-emit the zip
	///   file header to be consistent with the actual ZIP64 requirement.  But using a
	///   non-seekable output stream, the library cannot seek backward, so the header
	///   can never be changed. In other words, the archive's use of ZIP64 extensions is
	///   not alterable after the header is emitted.  Therefore, when saving to
	///   non-seekable streams, using <see cref="Zip64Option.AsNecessary"/> is the same
	///   as using <see cref="Zip64Option.Always"/>: it will always produce a zip
	///   archive that uses ZIP64 extensions.
	/// </para>
	///
	/// </remarks>
	public enum Zip64Option
	{
		/// <summary>
		/// The default behavior, which is "Never".
		/// (For COM clients, this is a 0 (zero).)
		/// </summary>
		Default = 0,
		/// <summary>
		/// Do not use ZIP64 extensions when writing zip archives.
		/// (For COM clients, this is a 0 (zero).)
		/// </summary>
		Never = 0,
		/// <summary>
		/// Use ZIP64 extensions when writing zip archives, as necessary.
		/// For example, when a single entry exceeds 0xFFFFFFFF in size, or when the archive as a whole
		/// exceeds 0xFFFFFFFF in size, or when there are more than 65535 entries in an archive.
		/// (For COM clients, this is a 1.)
		/// </summary>
		AsNecessary = 1,
		/// <summary>
		/// Always use ZIP64 extensions when writing zip archives, even when unnecessary.
		/// (For COM clients, this is a 2.)
		/// </summary>
		Always
	}


	/// <summary>
	///  An enum representing the values on a three-way toggle switch
	///  for various options in the library. This might be used to
	///  specify whether to employ a particular text encoding, or to use
	///  ZIP64 extensions, or some other option.
	/// </summary>
	public enum ZipOption
	{
		/// <summary>
		/// The default behavior. This is the same as "Never".
		/// (For COM clients, this is a 0 (zero).)
		/// </summary>
		Default = 0,
		/// <summary>
		/// Never use the associated option.
		/// (For COM clients, this is a 0 (zero).)
		/// </summary>
		Never = 0,
		/// <summary>
		/// Use the associated behavior "as necessary."
		/// (For COM clients, this is a 1.)
		/// </summary>
		AsNecessary = 1,
		/// <summary>
		/// Use the associated behavior Always, whether necessary or not.
		/// (For COM clients, this is a 2.)
		/// </summary>
		Always
	}


	enum AddOrUpdateAction
	{
		AddOnly = 0,
		AddOrUpdate
	}

}
